In 2015, Boris Johnson donned a jumpsuit, lifebelt, and crash helmet for an election photo opportunity on a hovercraft in Burnham-on-Sea.

If that was a predictable bit of Johnson electioneering, it is less the sort of thing that you might associate with Tim Farron. Still, last week, he followed in his Conservative counterpart’s footsteps, clambering on to the rescue craft and zooming around the treacherous mudflats of the Somerset coast with his party’s candidate for the Wells constituency, Tessa Munt.

There were jokes about floating voters, and politicians being full of hot air. Activists and party supporters were rallied. And then the circus moved on.

For Farron, the hope was to move the dial in a constituency that the Liberal Democrats badly want to win – and to provide a contrast with the stage-managed Theresa May, who lacks her foreign secretary’s enthusiasm for an improvised campaign stop. But in Burnham-on-Sea, the locals were not overly impressed – and their scepticism suggested something of the mountain the Lib Dems’ leader has to climb.

“I’m not saying Farron isn’t a good guy,” said Geoff Lewis, 60, the owner of the Treasure Chest gift and ice cream shop opposite the hovercraft slipway.

Facebook Twitter Pinterest Farron and Munt campaigning in Burnham-on-Sea. Photograph: Brad Wakefield/Rex/Shutterstock

But he is not convinced campaign stunts do much to help voters make up their minds. “Very few people around here even knew he was there. It all seems a bit silly really.”

The Lib Dems need to work hard on impressing people like Lewis. His is just the sort of vote they are desperate to have. And in Burnham-on-Sea, just as the Guardian found in the city of Wells last week, the fluidity of people’s voting intentions from one election to the next suggests that it is all to play for.

As a student Lewis voted Labour. But since those idealistic days he has always backed the Tories. Along with running the Treasure Chest (while the Guardian was there Lewis served visitors rum and raisin ice-cream, fudge and a phallic novelty marshmallow discreetly slipped into a brown paper bag) he and his wife buy and sell property.

Facebook Twitter Pinterest Geoff Lewis in his shop in Burnham-on-Sea. Photograph: Sam Frost/The Guardian

“We’re Tories through and through,” he said. “But I’ve become very cynical since the Brexit vote. Half the people didn’t know what they were voting for. When we come out they’ll be asking what’s happened to their cheap fags and booze. I’m more worried about security and what’s happening in eastern Europe. I bet Putin is loving all this.

“I’m not sure about Theresa May. I don’t know if she will get a good deal for business people if there is no effective opposition.” Nor is he convinced that the Lib Dems – the only party with a realistic prospect of challenging the Tories in Wells – are the answer. “I’m really not sure what to do.”

During the hovercraft stunt, Farron repeated what is fast becoming the Lib Dems’ riposte to May’s “strong and stable” mantra.

Facebook Twitter Pinterest The High Street in Burnham-on-Sea. Photograph: Sam Frost/The Guardian

Vote Lib Dem for a decent opposition even if you’re a natural Tory, he tells people – and make sure you elect an MP who will stand up for local needs, who will keep your hospitals open, your waiting lists down, your services intact. Munt tells everyone who will listen that her opponent, the former soldier James Heappey, is a yes man who will not challenge his own party.

In the city of Wells last week the Guardian found signs that these messages might be working. Even on the cathedral croquet lawn, where you might expect most players to be true blue, there was a whispered pledge from one middle-aged woman to secretly vote Lib Dem.

In Burnham-on-Sea the Lib Dem promises to defend services such as health and social care might prove to be a vote-winning message. By the year 2033 half the population of the resort and the nearby town of Highbridge is likely to be aged over 65. Many voters have migrated here from cities like Bristol and Birmingham to enjoy retirement in the sea air. In general they may be less liberal with a little “L” than those we met in Wells, who include incomers from London and the south-east. But in these changing times, the impression is that lots of votes many be up for grabs here too.

Facebook Twitter Pinterest The beach at Burnham-on-Sea. Photograph: Sam Frost/The Guardian

Just inland from where Farron and Munt were buzzing around on the hovercraft next to Burnham and Berrow golf course, there are row upon row of neat bungalows, with immaculate gardens mainly occupied by retired people.

Facebook Twitter Pinterest A gull pops in for chips in Burnham-on-Sea. Photograph: Sam Frost/The Guardian

Graham – not his real name – was cleaning out the gutter of his bungalow when the Guardian asked him to share his political opinions. He got down from his ladder and swore with surprising ferocity. “I’ve always voted Conservative,” he said, “But I’ll never vote for them again.”

He said his wife had a serious disability that left her confined to bed for two or three days a week. But Graham said she had been upset and humiliated at having to undergo what she saw as intrusive and insensitive Pip (personal independence payment) assessments to try to prove she was not faking it. Her payments were cut anyway. He won’t give his real name because he fears the authorities will target them further if he does.

“They stole her money,” said Graham. “I think the Tories are going for the people who can’t fight back. It’s made us less trustful.” But do the Lib Dem pledges to temper a Tory landslide cut through? “I don’t like their leader. I probably won’t vote at all.”

Facebook Twitter Pinterest Bernard Vowles. Photograph: Sam Frost/The Guardian

Bernard Vowles, an 81-year-old former trade unionist originally from Bristol, was polishing his car on the drive of his bungalow. He voted Ukip in 2015 – immigration is one of his big concerns – but the party is not putting up a candidate in Wells.

“Labour left the working man long ago and I’ve never voted Tory. I don’t think much of Tim Farron – he just looks like a boy to me.”

Facebook Twitter Pinterest Colin Rufus and Phillip Holland. Photograph: Sam Frost/The Guardian

Knowledgable and politically engaged, Vowles appeared to be the opposite of two 20-year-olds, Connor and Mitch, who spoke to the Guardian in Wells last week, and said they could not name the prime minister and had no intention of voting. But he revealed: “I’ve spent a lifetime telling people they have to vote but I may end up not voting, which makes me sad.”

On Golf Links Road, the retired joiner Colin Rufus was rebuilding the low wall between his front garden and that of his neighbour, Phillip Holland, a former soldier and teacher. The wall has collapsed, they say, because the pair spend so much time sitting on it chatting.

Both are concerned about space – Rufus argued the UK is becoming too crowded because of a free and easy immigration system; Holland, born and bred in Somerset, added that he was fed up with those arriving from other parts of the UK in search of peace and quiet. “They tell me they want to come here for the quality of life. I ask them if they have thought how they will affect the quality of the life of those already here.”

Rufus said he would probably vote Tory, while Holland is weighing up whether to back the Conservatives or Lib Dems. That wall between their properties might get more wear over the next few weeks.

There may be a glimmer of hope to be found in the county council election results for the Lib Dems earlier this month. The Tories held the Burnham-on-Sea North seat with a slightly reduced vote share – 48% against 50% in 2013. But the Lib Dems’ share was noticeably up at 38% compared with 27%.

In the tourist information centre, someone remembers that Farron isn’t even the first Lib Dem leader to take to the rescue hovercraft. A fresh-faced Nick Clegg joined Munt on it back in 2008.

The information centre is run by volunteers – a sign of local authority cuts. Margaret Fielder, a retired archaeologist, and Mary Lock, a former banker, both may be swayed by those Lib Dem arguments.

Facebook Twitter Pinterest Margaret Fielder and Mary Lock. Photograph: Sam Frost/The Guardian

Fielder pointed across the mudflats to Hinkley Point looming out of the haze in the neighbouring constituency of Bridgwater. A new nuclear power plant is being built there. “That’s a white elephant. They should be spending that money on health and social care, not on that blot on the landscape,” said Fielder.

The beach quickly returned to normal after Farron’s visit. Helen Meager, 41, was building what looked very much like a sandcastle but her three-year-old son Cai wanted it made clear that it was a car park.

Meager reels off the issues she is concerned about – education cuts, GP waiting times, infrastructure, Hinkley Point. She would like to vote Green but sees it as a wasted vote here. “I’ll probably have to go for the Lib Dems.”

Facebook Twitter Pinterest Helen Meager and her son Cai. Photograph: Sam Frost/The Guardian

The Lib Dems’ pledge to protect local services might also chime with people such as Dave Furber, who patrols the beach up near Brean Down on the north-west tip of the constituency. Like the hovercraft crews Farron met, he and his colleagues spent a lot of time saving visitors from the mud. They call the visiting 4x4 drivers who get stuck the “Birmingham navy”.

Furber is also concerned at austerity-fuelled cuts, claiming the beach patrol was threatened by lost local authority funding until one of the local sprawling caravan parks stepped in to help. “Lives would have been lost if they hadn’t,” he said. Furber’s vote is still there to win – and, like so many others around here, suggests a contest that will continue to the very end. “I leave it to the very last minute,” he said. “I go into the voting booth and make up my mind there and then.”