The landscape remains as it was then,” says Mark Worthington, waving across marshland and poplar trees laden with mistletoe. He stands beside Pegasus Bridge, across the Caen Canal at Ranville, Normandy, taken on 5 June 1944 by an allied advance party that arrived to clear the way for D-day, and the liberation of western Europe.

Worthington, curator of the Pegasus Bridge commemorative museum on this site, proceeds to the cemetery of British soldiers killed on, or soon after, D-day – rows and rows of lost lives. In the graveyard of the lovely church next door “are German graves, and that of the first man to die at D-day, on Pegasus Bridge, Pte Den Brotheridge” – of whom a statue was unveiled in Portsmouth during the week of our visit to Ranville, where it later went for display. This June marks the 75th anniversary of D-day, last of the commemorative five-year “big ones”, which will be attended by heads of state and veterans alike.

But there is this other thing hanging in the misty coastal air – Brexit, and its effect on the bond forged by D-day. This strangeness propelled a friend and colleague, Rémy Ourdan, of Le Monde, and I to travel both coasts – English south and French north – and report for our respective papers on their shared sea and history of interdependence and rivalry.

We had the idea in Bayeux last autumn, from where the tapestry of the Battle of Hastings will travel to England, on a date to be arranged. Aware of its history, distant and recent, Bayeux is a town strewn with union jacks, stars and stripes and Canadian maple leaves, plus flags of all countries in the European Union. I tried to imagine an equivalent scene on the English south coast, and could not.

Neither can Worthington, from a Royal Navy family in Dartmouth, married to Nathalie from France, whom he met through a twinning exchange, and who curates another museum at Juno Beach. “I look at Britain as a European now,” says Worthington, “with not a little despair”.

“I owe my marriage to town-twinning”, says Nathalie, “and coming from here, feel protected by Europe. Pegasus Bridge should be built between France and England.”

Ranville is one of 70 memorial sites and museums across Normandy that commemorate what in France is called the Bataille de Normandie. And here, visiting, are three British veterans, including Frank Prendergast, one of 600 soldiers of the 7th Battalion, Parachute Regiment, who landed on Pegasus Bridge – 400 were killed – and a freeman of Normandy. “Pegasus Bridge had to be taken and held,” he says, “to keep German tanks off it – otherwise, no D-day.” He returns every year: “I love France, so many friendly faces. It’s hard – I’m usually the first person to cry – but the welcome is amazing, and they take what happened so seriously.

On Brexit, Prendergast is tactful: “We all make mistakes, don’t we?” Questioned by schoolchildren next morning, he is more robust: “Britain managed without Europe for thousands of years, and can again.”

From left: Frank Prendergast, with fellow veterans Fred Glover and Bill Gladden

The Memorial Museum in Caen is one of the great warfare museums of Europe; its scope widened and deepened to incorporate the setting of Holocaust by the passionate curator Stéphane Grimaldi. “Your south coast was for four years a first line of defence, facing an enemy,” he says. “Then Churchill helped save Europe, and said that Britain would be part of a Europe rebuilt by a Franco-German alliance. But I’m not sure the English realise that, preferring to see in him only the patriot”.

The Battle of Normandy has another narrative: Grimaldi has opened a further museum at Falaise, birthplace of William the Conqueror and site of a battle in which two-thirds of the city was destroyed by the allies. France lost 20,000 civilians during “liberation”, mostly to allied bombing, and they are the theme of this endeavour. Caen, too, was 35% ravaged, and the historian Anthony Beevor caused controversy ahead of the 65th D-day anniversary calling the bombing of Caen “close to a war crime”.

“These were sacrificed people,” says Grimaldi, “forgotten by history, which must always revisit itself in pursuit of truth.” He cites the trailblazing work of historian Jean Quellien, who “counted the dead, village by village, during the 1970s – the first time anyone had confronted that narrative”.

But public consciousness is more informed by ties to Britain, as we head west to Bayeux to meet keeper of museums Antoine Verney. “Here, we are deeply anglophile,” he says. “Look at our history: the Norman invasion, the hundred years war – but then the liberation, which defines our relationship.” Bayeux was taken without bombardment.

A statue on a roundabout on the outskirts of Bayeux depicts a soldier from the town’s famed tapestry

Brexit makes an ironic context for the loan of Bayeux’s tapestry, but local reporter Pascal Vannier says: “In this area, no one really talks about Brexit, and if they do, it’s: ‘Fuck it, let them leave’. But to an anglophile like me, it’s very strange – the sea between us brought us freedom.”

Le Havre is the French coast’s most charismatic city, Europe’s fifth port. It was once gateway to the world, along with Naples and Liverpool; from here, millions left to become America’s huddled masses. And like Liverpool, Le Havre embraced black blues and rock music from America faster than any French city – Paris was a jazz town – and that’s what Roberto Piazza, AKA Little Bob, talks about, at home beside the old bell tower on the docks, which summoned workers each grey dawn.

“Look!” – he leafs through his scrapbook – “350 English gigs in four years. I was bigger there than in France – the Marquee, 100 Club, Roundhouse, Dingwalls eight times!” Lemmy Kilmister played on his album of 1987, Ringolevio. “Rock is American and English, and we understood that immediately in Le Havre. Bands like the Stranglers would play here to warm up their most devoted fans in France and get a feel for it before heading on to Paris” – where Little Bob opened for them at the Olympia. On Brexit: “England made me, man – what the fuck are they doing? We love England – what’s the problem?”

Le Havre has its Simenon, crime-writer Philippe Huet, whose thrillers La nuit des docks and Les Quais de la colère constitute a Normandy noir. “People in Normandy turn their backs to the sea. Only Le Havre feels open to the oceans,” says Huet.

Rock singer Little Bob in Le Havre, France

But Le Havre’s “liberation” was a bitter one: whereas Caen and Falaise were bombed as part of the June advance, German “fortress” Le Havre was assailed from 29 August, after the allies had refused an evacuation of civilians offered by its commander. Some 2,000 were killed – and 19 German soldiers. “When the British entered Le Havre,” continues Huet, “there were no flags, no cheering – only an atmosphere of mourning.”

Elisabeth Coquart co-wrote books with her husband, Huet, among them the nonfiction Le Jour le plus fou: 6 juin 1944, Les Civils dans la tourmente (the maddest day: civilians in torment), published in 1994 and described as “the saga of the no-ranks who found themselves face to face with great history stuffed with glory and covered with medals. They tell it differently.”

She adds, on the current situation: “I’m sick of Brexit. If the English want to blame all their problems on Europe, then that’s another of their problems.”

Yet there is this connection: “Before 1872,” says Huet, “there was no football in Europe until the British started playing on Avenue Foch – and thus European football was invented: Le Havre Athletic was the first football club in Europe, thanks to the British.” The modern-day anthem of Le Havre AFC is sung to the tune of God Save the Queen.

Gilles Perrault, a novelist living at Sainte-Marie-du-Mont on the Cotentin peninsula nearby, recalls a nightclub in the 1980s called Exocet, after the French missile used against British forces in the Falklands: “They all supported Argentina,” he says. And Brexit? “If the English economy collapses, they deserve it. Who do they think they are?”

A woman walks her dogs near the coast at Ouistreham

We had arrived in Normandy from the northeastern coast, at Calais, where Rémy met me off a Eurostar so quick from London there’s barely time to browse Le Monde. But the ease of that crossing contrasts brutally with that to which residents of the now dispersed “jungle” aspire in the opposite direction – and sometimes pull off, thanks to derring-do, smugglers and luck. This is the new story of the shared sea, which occupies Laurient Caffier, a “humanitarian” smuggler who loses rather than makes money. He bought a boat, in which he shipped eight Iranians to Britain, with whom he maintains contact, in Farsi. A second voyage was intercepted, however, and Caffier given a six-month suspended sentence.

He shows pictures of the tortured bodies of his passengers – “persecuted because they were Christians”. Do you yourself believe? “No, I do this because they were tortured, not because they were Christians.” As for Brexit: “The harder the barrier, the greater the risk – and the higher the mafia’s price.”

We drive through Le Touquet – “Paris-Plage” – with its Westminster hotel, and Dieppe, where the Victorian fashion for sea bathing at Brighton was first imitated on the continent, and where impressionists from both countries convened to paint.

Back in Caen to catch the ferry to Portsmouth, there’s a final conversation with geographer Pascal Buléon, who co-authored (with his counterpart Louis Shurmer-Smith in Portsmouth) an atlas of what the French call La Manche – the sleeve – and we call the English Channel. It is bilingual, entitled in English Channel Spaces: a World Within Europe. “Eighty per cent of the world’s trade is done by sea,” says Buléon, “and 20% of that passes through or across the channel.” It is the busiest in the world, the waters are “very efficiently run, along what in France is called Le Rail – the sea lanes. It’s impressive that we don’t have shipwrecks.”

Shortly before dusk, we board at Ouistreham, port of Caen; it’s always an emotional moment. Hundreds of times I’ve sailed by ferry across this sea: in my childhood and 20s, the ferry was where life began; the “boat-train” to Paris and points south. Days when I wore Kickers shoes even though I didn’t like them, because they looked “continental”, and bought my first car, a Citroën 2CV with the steering wheel deliberately on the left, “wrong” side.

On the ferry from Ouistreham to Portsmouth

But never had I been in the wheelhouse, and I tell Cdr Pierre-Marie Lejosne of Brittany Ferries’ Mont St Michel: “This is my boyhood dream come true”, though I preferred sailing in the opposite direction. There are more computer screens than wheels now, but still that focus among the crew, salty sea-dogs even in the 21st century. The wind is high, sea rough, spray wild – and a rainbow emerges from the heaving water.

Lejosne joined the line in 1991 as an officer from maritime school in Le Havre: “I’m a citizen of France,” he says, “but my life is on the sea.” Of Brexit: “England has always been an island, will remain an island and will need a rapport with the world.”

The lights of Portsmouth come into view as the words of that Bayeux reporter Vannier come to mind: “If you asked French people to name the port from which the D-day force sailed, hardly anyone would know.”

Buleon’s co-author of the channel atlas, the distinguished British geographer Louis Shurmer-Smith, is an OBE and has an honorary doctorate from Caen, where he is known as le Passeur – the ferryman, or smuggler, “of people and ideas across the channel,” says his wife Pamela, also a geographer.

“Seas,” he says, “have a tendency to separate people, while my life’s work has been to bring them together.” Shurmer-Smith has brought scores of students – and their research – to and fro under the Erasmus scheme, from which British youth now faces exclusion. “For a while, I was literally commuting on the ferry.”

But then he tells about a commission from Hampshire county council for a map of the county’s coast opposite that of Normandy. “They wanted the two coastlines to be symmetrical, but they couldn’t be: the French side is longer. Their suggestion: ‘Make Hampshire bigger’.”

The second world war has enthralled British imagination of late. We’ve gone from the country of My Beautiful Laundrette and Trainspotting to that of The King’s Speech, Dunkirk, Churchill and Darkest Hour within a year of each other – plus Journey’s End and Victoria and Abdul. Our war is less about its causes than about us.

Portsmouth’s D-Day Story museum has been revamped with families, schools and young people in mind, says Jane Mee, who is responsible for the relaunch at Portsmouth city council. “We wanted to bring the story alive, for young people to look for themselves at the story of servicemen their own age. It’s like reality TV. This is not the whole of world war two. It’s about D-day, honour, courage, even human frailty.”

Curator Andrew Whitmarsh says: “We wanted to tell a clear story, and you cannot do that if you broaden it too much.”

Rémy was surprised not to encounter more on the reasons for landing in Normandy, nor even the word “Holocaust”. Stéphane Grimaldi, who worked with the redesign team in Portsmouth, had said: “I kept emphasising that the liberation of Europe began on the site of your museum, but couldn’t get that across. The project had no ambitions towards the wider context, and that’s very British.”

Visitors at the D-day museum in Portsmouth

Portsmouth became the first local authority to unilaterally “leave” the EU in 2016, urging citizens to vote to do so. On referendum day, the local paper carried one word across its front page: NO! The city voted 58.1% Leave.

The 2016 motion was secured by then Conservative leader Donna Jones. “Portsmouth,” she says, “has existed for a thousand years, part home to the Royal Navy. A military city, garrison town until recently. We are a predominantly white population, about 93%.”

But “our history is by the water and is made by what we make of that water. Trade is key to our destiny.” So why leave the EU? “Because of the unevenness of it. It just doesn’t fit Britain.”

The city leader is now Lib Dem Gerald Vernon-Jackson, who calls the 2016 manoeuvre “an operation by the Tories and Ukip. I’m only leader of this council because last year, six particular wards were up for re-election. If it had been all of them, Portsmouth would be a Ukip city.

“Perhaps all this is happening because we’ve never been recently invaded, and have no idea what that does to a civilian population, no idea of the carnage Europe has endured. One of the things that built the EU was knowledge of the cost of war.”

Vernon-Jackson enjoys exploring France’s Normandy coast and D-day museums. “Seventy there, one here. I think it’s about the liberation of Europe and defeat of fascism – a contribution to the whole. But most people here do what the Americans do: rewrite history to make it all about ourselves.”

Council leader Donna Jones on the ramparts of the Tudor fort in Portsmouth

Like almost every civic hall in Britain, Portsmouth’s flies the union flag without Europe’s stars beside it, as would feature on every municipal building in Europe. Next door is a pub proclaiming itself “Isambard Kingdom Brunel Free House”. It isn’t: it is Portsmouth’s branch of Wetherspoons, in which the chain’s owner, Tim Martin, launched his no-deal Brexit campaign tour in January.

Rob Silvester knows his mind. He was a leader of the fearsome Portsmouth FC 6.57 crew – named after the first train to Waterloo – which blazed a trail of aggro during the 1980s and 90s. He wrote a good book, Rolling With the 6.57 Crew, which mostly details fighting between Englishmen, but contains a bumptious account of the rout of Le Havre and Honfleur by Pompey fans on a day out to get a “friendly” match abandoned.

Now, Silvester’s Twitter feed mostly features his new cause: Ulster and UVF veterans. We met in 2003 when Portsmouth were on the eve of their first Premiership season, on which occasion he said, presciently: “Britain is an island, and Portsmouth an island within an island.”

We reconvene at the Electric Arms pub on Fratton Road, and it needs explaining to Rémy “that while everyone else gives the finger to say ‘fuck off’, we English give it two. Because when the French captured an English archer, they chopped off his fingers. But before Agincourt, the English showed ’em: ‘We’ve got the fingers’” – and Rob rolls a sleeve to reveal his tattoo: the archer’s “fuck off”.

Rob Silvester of the Portsmouth ‘6.57 crew’ shows off his ‘Agincourt’ tattoo

Silvester is too intelligent to rant. “I love France,” he says, “my dad took me to the Normandy beaches, and I take my son. And the closest I’ve been to tears recently was in Emsworth: this man with his medals on, in the supermarket. He’d been a sapper for the Royal Engineers, first on the beaches.”

“I’m a patriot,” he says, “I love my country. I don’t do politics, but Brexit is all about our identity. Britain invented the world, and it’s a mythic power.” After a few pints he laughs amicably with Rémy: “France, well, it’s just over the road. It’s a deep down hatred ain’t it?”

We proceed to the Mother Shipton, where last orders are a movable feast, and gracious hostess Andrea engages Rémy: “Do you live in Paris?” “Yes”. “Do you have children?” “Yes.” “Aren’t you worried about them being raped by refugees?”

If Le Havre has Philippe Huet, Portsmouth has Graham Hurley, whose south-coast thrillers, featuring detective Joe Faraday, have been adapted for French television and transposed to Le Havre as Deux Flics Sur Les Docks.

Hurley and his wife Lin moved along the coast to Exmouth, and sweeping views of the Exe estuary. Wetherspoons’ Martin is a neighbour and East Devon voted 54.1% Leave, despite the Remain university city of Exeter. “It’s deep Devon farming Brexit,” says Graham, “voting against all those subsidies they’ve enjoyed. But good air, the end of the line, I like that.”

Hurley has just received a letter from the mayor of St Gobain, Normandy: a roll of film was uncovered, which turns out to be one taken by Hurley for D-day commemorations of 1984. The mayor asks: would Hurley present a screening this anniversary summer 10 years later, “to emphasise the connections that unite us” in this time of Brexit? “Can you imagine that letter arriving in France from the mayor of a south-coast town in England?” asks Hurley.

On the seafront at Portsmouth

“Portsmouth” he says, “is the perfect place to observe Britain en pleine dégringolade – falling apart. As my detective does: alcohol, drugs, family breakdown. It’s all there in Portsmouth, inward-looking, claustrophobic, surrounded by fortresses.”

He recalls “a survey in primary schools: what frightens you most? First was drunk people. Second, the French. Because they talk funny.”

It is, he says, “a deepening of the dyke, higher than ever. Since I wrote those books, Britain has become one big Portsmouth.”

Along the Dorset coast at Weymouth, Just Military regalia shop on the pretty harbour side, sells Nazi daggers and SS uniform patches. Quite apart from that, Weymouth and Portland voted 61% to leave, among them Bert Lynam and Kelvin Moore, securing their fishing boats Jodye B and Rampant. It was off this coast that all-out scallop war with French counterparts erupted last August. “That’s why we’re leaving ain’t it,” says Lynam, “to get our waters back.” He explains: “We have an exclusion zone of six miles, while they have a 12-mile exclusion – well, that’s not right for a start, is it?”

But not all their complaints are directed at Brussels. EU quotas, says Moore, are so quickly met by large British ships that “there’s nothing left for us little ones”. Moreover, adds Lyman, “the quotas that IFCA (regional Inshore Fisheries and Conversations Authorities, which try to conserve stocks) give us are just as severe.”

A fisherman in Weymouth

Brighton is an anomaly along the coast, counting the only parliamentary constituencies to vote to Remain – apart from Falmouth and Truro – by 68.6%. The town of Graham Greene’s Pinkie is now capital of British bohemia, singularly tatty but chic. And if funky Brighton plays jester to the patriotic coastline, its jester residents are the cartoonists, Steve Bell of the Guardian and the Observer’s Chris Riddell – those who tell truth to power by laughing at it.

Riddell, until recently children’s laureate, receives us in the wonder of his studio. “We have wonderful murmurations of thousands of starlings here in Brighton, but also murmurations of people,” he says. “Brighton is cosmopolitan, tolerant – has been since the 60s and 70s, when so many of us came as students and never wanted to leave.”

The Big Issue and the union jack in Remain-voting Brighton

But there’s no port; Brighton’s cosmopolitanism comes from leisure and learning, and being what Riddell calls “London-on-Sea”. On the other hand, he adds: “There’s terrible deprivation. I do live drawing gigs on estates where children have never even got as far as the sea.”

Brexit is “a fault line,” says Riddell, but for a cartoonist “also a godsend. It’s our privilege to be able to portray something without having to describe it, and Brexit has all the metaphors we could ask for: we’re actually going over our own white cliffs of Dover!”

Arron Hendy, editor of the Argus in Brighton, is a man of the entire coast: born in Weymouth before his career proceeded eastwards to Bournemouth, thence Southampton, finally here. “Bournemouth’s more well-to-do, but Southampton’s another thing: I covered the crime beat, a place of petty squabbles that became major violent incidents.”

Why did the coast vote Leave? “Age played a part. A lot of retired people who are bored and don’t like foreigners. I’m not sure that coastal towns do look out to sea. There’s no connection between this coast and France. Not many people could name five places on the other side. We used to have pen pals we’d write to and stay with – not any more.”

For all the cosmopolitanism, Brighton still has that edge, and I posit that Pinkie never really left. “Pinkie never left,” agrees Hendy, “but he’s not at Kemptown races, more likely out on a stag night. And so many others arrived – this is the San Francisco of the south coast.”

The coast road from Brighton to Dover is a quintessentially English corridor of B&Q and KFC, thickets of union flags and St George crosses. I’d warned Rémy along France’s open roads about the ghastly congestion along ours, and against taking a train: that morning’s edition of the Argus had a wraparound cover on the latest rail failures.

Traffic and traffic jams of a different kind are at issue in Dover, through which 17% of all UK trade passes.

An English flag hangs from the balcony of a house in Dover, as cross-Channel lorries pass

People here know all about Operation Stack, whereby motorways become waiting lanes when weather prevents ferries from sailing. They are familiar with signs reading: “Port of Dover. Traffic management and berth improvements. Co-financed by the European Union”, with a flag of circled stars – for now.

There are stars, too, on a wall – but one is being chipped away by a man on a ladder: not for real, but in Banksy’s marvellous mural.

Dover voted Leave by 62.2% – and Sam Lennon, veteran reporter on the city for the Kent Mercury group, says what everyone thinks: “no one has a clue what’s going to happen.” He cites one report predicting: “one-minute delay in customs means a 20-mile tailback”. “You’d be surprised how little contact there is between here and Calais, although it’s our twin,” he says. “I don’t know anyone who goes for business, and you don’t hear French in Dover. It’s a place of passing through, and I think the drawbridge will come up after Brexit.”

Richard Christian – head of communications for the Port of Dover – is son of a clergyman and descended from Fletcher Christian, who led the mutiny on the Bounty. “I’m surprised they gave me job on a docks!” he jokes.

The figures are staggering: “The naked eye does not see what is actually happening,” says Christian. Each year, 11.8 million foot passengers and 2.5m trucks pass through “with at least one person in each – up to 10,000 lorries on a busy day”. And the crunch: “98% of goods that pass through Dover is trade with the EU.”

“We’ve always said that whatever happens post-Brexit, we can maintain the flow, if pre-declaration of goods and pre-clearance are done away from the port. There can be no additional checks at the actual border,” says Christian.

The economy depends on a functioning port, such as “the automotive industry, where assembly lines operate with tiny windows for parts delivery, otherwise they break down. We might be on the sea, but we must function like any landlocked country.”

Banksy’s mural of EU stars decorates the approach to the docks at Dover – where 62.2% of the population voted Leave

Wind cuts the surf, and rain falls without relent; ferries are delayed and access to the port gridlocked, affording a glimpse of what Dover faces if the pre-clearance scheme is not arranged. Don Harris waits in a hotel lobby to board the ferry on which he works – “supposed to have left this morning, but stuck in Dunkirk.”

“I used to work in the port”, says Anna at reception. “I know what it’s like backed up – always worse on Tuesdays, for some reason.”

“Nah”, retorts Don, “it’s Remain scare tactics – we’ll be fine” – and we discuss Banksy’s mural. “At least the man on the ladder’s getting on with the job!” says Don.

The journey from Bayeux to Banksy might as well end at the beginning. A lone, modest but elegant, commemorative column on the beach at Houlgate marks the point of William the Conqueror’s departure, with 700 warships, to invade England. They landed on 28 September 1066 and – as every schoolchild is taught – routed King Harold’s English army at Battle, near Hastings.

At the museum in William’s castle at Caen, curator Jean-Marie Levesque waves towards his wall of books and journals: “About 85% of them are in English,” he observes. “There’s a strange fascination with that defeat.”

Levesque points out that “people know less about the violence of the Norman conquest – more about the Domesday Book”, and he’s right: the two invaders – Normans, and Romans – founded Britain on the basis of our subjugation, but we prefer not to see it that way.

When the Battle of Hastings is re-enacted each year at Battle Abbey and Battlefield, crowds “cheer King Harold and boo William”, says Roy Porter, curator of English Heritage buildings in the south-east.

He takes us to the Abbey grounds where Harold fell, and around the battlefield, casting a scholarly eye over events of that day: “You don’t get any English account until 60 years later.”

In the Carmen de Hastingae Proelio by Guy, bishop of Amiens, “Harold is not shot in the eye,” says Porter, “he’s hacked to death with axes.” Unlike the most famous depiction of a battle ever rendered: the tapestry en route for Britain and, Porter hopes, Battle Abbey.

On the ramparts at Caen from which William himself gazed seaward, I venture to suggest to Levesque: most kind of your president and colleagues to lend the tapestry, despite the affront of Brexit, but what we really need at this juncture are the 700 warships and another invasion from this shore. “We’ll be accepting refugees,” he replies, with a half-smile.

The French view, by Rémy Ourdan of Le Monde

Ed Vulliamy and I travelled to Normandy twice last year. The first time was in June, around the time of the D-day commemorations, for a conference on the Bosnian war – a conflict we both covered 25 years ago – at the Memorial Museum in Caen. The second time was in October for the Bayeux awards for war correspondents. It was then, at the bar of the famous Lion d’Or hotel, where both De Gaulle and Churchill had come during or after the second world war, that Ed suggested we visit the Channel coasts together before Brexit. The idea was to travel both coasts in search of what, over centuries, has brought the two countries closer, and what drives them apart. We travelled, one could say, between the historical bookends of William the Conqueror and D-day.

Two battles – Hastings in 1066 and Normandy in 1944 – that changed for ever the destinies of the two countries, and, in the case of the latter, the destiny of the world. Two landings also both on the news agenda: 1066 with President Macron’s promise to loan the Bayeux Tapestry to England after the rupture of Brexit, and 1944 with the 75th anniversary of D-day on 6 June.

We visited historians, museum directors, geographers, writers, and people more concerned by recent history and current affairs such as port administrators, fishermen, rock singers and football fans. We listened to stories about centuries of war and hatred, from anglophiles on the French coast and francophiles on the British one. We met French-British families, for whom Brexit is a tragedy, regardless of whether they feel “European”, and those with both pro and anti-Brexit views on England’s south coast.

A statue of a Norman soldier in action on the site of the Battle of Hastings in Kent

People living on both coasts talk about the age-old enemy and shared history, but the conclusion of the trip might be that they don’t really know each other, or don’t really care about each other.

The articles in Le Monde were published two weeks ago, on 11 and 12 April, as a series. 12 April was one of the deadlines for Brexit, ultimately postponed again. In Paris, where very few people would know about 1066 or the hundred years war, readers were impressed with how local and family memories in Normandy could still invoke centuries-old conflicting stories.

French readers wrote to me saying they never thought about the 20,000 civilian casualties of the Battle of Normandy in 1944, killed by the British and American liberators of Europe – a kind of taboo in France, but a memory still very much alive from Caen to Le Havre.

This trip reminded us that whether one is pro or anti-Brexit, pro or anti-European Union (and some of the French people we met would for sure be “Frexiters” if they had the chance), that shared history is a centuries-long process.

However passionate people in the UK are today about Brexit, Nathalie and Mark Worthington, a French-British couple who both curate second world war museums in Normandy, told us, while walking in the Ranville war cemetery (where lie the British soldiers killed during the capture of Pegasus Bridge, a few hours before the D-day landing): “When we are angry or when we simply have a bad day, we come to take a walk here, between the first soldiers killed for the liberation of Europe. We will never live through worse than what they lived through.”