“A triumph for UK diplomacy”, is how the expulsion of more than 100 Russians from more than 20 countries is being presented by the Prime Minister and her Foreign Secretary. And, in a way, it is.

Those who have given marching orders to Russian diplomats – commonly referred to in official statements as “undeclared spies” (note: declared spies – good; undeclared spies – bad) include a majority of our European Union partners, the US, Canada and Australia, as well as Nato headquarters.

Let me observe only as an aside that things have come to a pretty pass when the tally for expelled diplomats – a number that is likely to be doubled when Moscow gets round to retaliating – is regarded as a benchmark of diplomatic success.

It might rather be seen as the reverse: an actual failure of diplomacy. But there we are. It rather depends who is the target of your diplomacy, and in this case it was obviously not Russia, which is charged in the court of politics with the Salisbury poisonings, but our EU partners, other friends (Ukraine) and Nato allies.

And one reason – perhaps the reason – why this is being touted in London as such a triumph is that it allows Brexiteers to counter one of the most insistent charges of the Remainers: that this country’s international clout will be severely diminished by our departure from the European Union.

Some of the most bullish in the Leave camp are even arguing that it will be enhanced. At a time when both Theresa May (suspected of being “soft” on Brexit) and Boris Johnson (accused of bumbling incompetence) were politically under the weather, you can understand why the Western chorus of Russia-bashing comes as music to their ears.

How close, though, are appearance and reality? For a start, uniting a quorum of Western countries around vilification of Russia is not the hardest of sells, especially now Vladimir Putin has just won another six years in power.

Come on, you can imagine the British persuaders saying, you may not quite accept that the Kremlin spread novichok in Salisbury, but doesn’t it make sense to tell Putin that his new term gives him no mandate to mess with the West?

Even then, however, the UK had to expend some effort (and political capital, perhaps, too). As surprising as the West’s near-unanimity is now, nearly four weeks on from Salisbury, was the hesitancy of even our closest allies at the start.

The initial response seemed to be that whatever happened in Salisbury was between the UK and Russia, and that if London wanted wider support, it had to produce some evidence.

Evidence may or may not be what the Prime Minister produced over dinner in Brussels – and if it was, it would have been courteous to give the UK public some of it, too. But it is not hard to imagine other UK arguments.

How about: “First they come for swapped spies in Salisbury, but next time it could be Stuttgart or St Etienne.” Or this: “Curbing chemical weapons has to be a collective endeavour; what message will it send if you don’t join in?”

Plus, there can be few Western countries that do not have at least Russian “diplomat” they would prefer not to have. So why not use solidarity over the Skripals’ poisoning as a pretext?

In other words, persuading Western countries to expel some Russians is probably not the hardest task in the world, especially not if you couch the arguments in the right way, with the clincher being “it won’t cost you much”.

Which it won’t – not even the UK. On the same day that Theresa May was announcing the expulsions and a few less obvious measures, the Russian energy behemoth Gazprom was raising a €750m (£656m) Eurobond in the City.

And no sooner had Germany told four Russians to go, than it gave the go-ahead to the contentious second Nordstream gas pipeline that will allow Russian gas exports to bypass Ukraine.

The biggest issues facing UK on leaving EU Show all 8 1 /8 The biggest issues facing UK on leaving EU The biggest issues facing UK on leaving EU Post-Brexit immigration workers sorting radishes on a production line at a farm in Norfolk. One possible post-Brexit immigration scheme could struggle to channel workers towards less attractive roles - while another may heighten the risk of labour exploitation, a new report warns. PA The biggest issues facing UK on leaving EU Customs union A key point in the negotiations remains Britain's access to, or withdrawal from, the EU customs union. Since the referendum there has been hot debate over the meaning of Brexit: would it entail a full withdrawal from the existing agreement, known as hard Brexit, or the soft version in which we would remain part of a common customs area for most goods, as Turkey does? No 10 has so far insisted that “Brexit means Brexit” and that Britain will be leaving the customs union, but may be inclined to change its position once the potential risks to the UK’s economic outlook become clearer. Alamy The biggest issues facing UK on leaving EU Northern Ireland-Irish border Though progress was made last year, there has still been no solid agreement on whether there should be a hard border between Northern Ireland and the Republic of Ireland. To ensure borderless travel on the island, the countries must be in regulatory alignment and therefore adhere to the same rules as the customs union. In December, the Conservative Party’s coalition partners, the DUP, refused a draft agreement that would place the UK/EU border in the Irish Sea due to its potential to undermine the union. May has promised that would not be the case and has suggested that a “specific solution” would need to be found. Getty The biggest issues facing UK on leaving EU Transition period Despite protests from a small number of Conservative MPs, the Government and the EU are largely in agreement that a transitional period is needed after Brexit. The talks, however, have reached an impasse. Though May has agreed that the UK will continue to contribute to the EU budget until 2021, the PM wants to be able to select which laws made during this time the UK will have to adhere to. Chief negotiator Michel Barnier has said the UK must adopt all of the laws passed during the transition, without any input from British ministers or MEPs. EPA The biggest issues facing UK on leaving EU Rights of EU citizens living the UK The Prime Minister has promised EU citizens already living in the UK the right to live and work here after Brexit, but the rights of those who arrive after Brexit day remains unclear. May insists that those who arrive during the transition period should not be allowed to stay, whereas the EU believe the cut-off point should be later. Getty The biggest issues facing UK on leaving EU Future trade agreement (with the EU) Despite this being a key issue in negotiations, the Government has yet to lay out exactly what it wants from a trade deal with the EU. Infighting within the Cabinet has prevented a solid position from being reached, with some MPs content that "no deal is better than a bad deal" while others rally behind single market access. The EU has already confirmed that access to the single market would be impossible without the UK remaining in the customs union. Getty The biggest issues facing UK on leaving EU Future trade agreements (internationally) The Government has already begun trying to woo foreign leaders into prospective trade agreements, with various high profile state visits to China, India and Canada for May, and the now infamous invitation to US President Donald Trump to visit London. However the UK cannot make trade agreements with another country while it is still a member of the EU, and the potential loss of trade with the world's major powers is a source of anxiety for the PM. The EU has said the UK cannot secure trade deals during the transition period. EPA The biggest issues facing UK on leaving EU Financial services Banks in the UK will be hit hard regardless of the Brexit outcome. The EU has refused to give British banks passporting rights to trade within the EU, dashing hopes of a special City deal. However according to new reports Germany has suggested allowing trade on the condition that the UK continues paying into the EU budget even after the transition period. Getty

One conclusion that could be drawn is that anyone, Brexit-Britain included, can exert influence on others, so long the message chimes with their interests and there is little or nothing to pay.

But another is that UK diplomacy will probably have to work much harder in the time of Brexit. Support was hardly spontaneous or fulsome, and we don’t know what inducements the UK may have offered. And, of course, it’s easier if the target is generally unpopular.

Those who felt that it was not in their interests to join the protest did not come on board. So how would it be trying to drum up some concerted action against China? Or against the EU, or an EU member, once we have left? And was there perhaps an element, this time, of the EU trying to drive home the message that such support is conditional on membership?

It is probably true that the UK will retain some clout in the area of security and intelligence, though that could be more problematical if transatlantic relations are cool. But what of trade – vis-a-vis a tariff-happy United States – or a China that imposes terms only a fraction short of dumping?

Today’s members have made clear that there is no rebuilding the Commonwealth, old or new. Australia and others had to restructure their trade after the UK joined the EU; there is no prospect of their reversing track now.

Not only will the UK have to work harder, but size and perceived allegiances will matter. Russia can cope with expulsions, especially if it gets its way on Gazprom and Nordstream. Is there not a danger the UK could get “picked on”, and not just by Russia, if its commercial alliances are all ad hoc?

Countries join UK expelling Russian diplomats over spy poisoning Show all 24 1 /24 Countries join UK expelling Russian diplomats over spy poisoning Countries join UK expelling Russian diplomats over spy poisoning United States Donald Trump has expelled 60 Russian diplomats from the US and closed the consulate in response to the Sergei Skripal spy poisoning. AFP/Getty Countries join UK expelling Russian diplomats over spy poisoning Great Britain Prime Minister Theresa May confirmed Britain would be expelling 23 Russian diplomats. AFP/Getty Countries join UK expelling Russian diplomats over spy poisoning Ukraine Ukrainian president Petro Poroshenko has expelled 13 Russian diplomats. Getty Countries join UK expelling Russian diplomats over spy poisoning Germany Germany's Chancellor Angela Merkel has expelled 4 Russian diplomats. AFP/Getty Countries join UK expelling Russian diplomats over spy poisoning France France's President Emmanuel Macron has also expelled 4 Russian diplomats. Reuters Countries join UK expelling Russian diplomats over spy poisoning Poland Poland's President Andrzej Duda has expelled 4 Russian diplomats. AFP/Getty Countries join UK expelling Russian diplomats over spy poisoning Lithuania President of Lithuania Dalia Grybauskaite has expelled 3 Russian diplomats. Getty Countries join UK expelling Russian diplomats over spy poisoning Czech Republic Czech Republic President Milos Zeman has also expelled 3 Russian diplomats. AFP Countries join UK expelling Russian diplomats over spy poisoning Netherlands Netherlands Prime minister Mark Rutte has expelled 2 Russian diplomats. AFP/Getty Countries join UK expelling Russian diplomats over spy poisoning Latvia Prime Minister of Latvia Maris Kucinskis has expelled 1 Russian diplomat. Getty Countries join UK expelling Russian diplomats over spy poisoning Estonia Estonia's Prime Minister Juri Ratas has expelled 1 Russian diplomat. AFP/Getty Countries join UK expelling Russian diplomats over spy poisoning Croatia Croatia President Kolinda Grabar-Kitarovic has expelled 1 Russian diplomat. AFP/Getty Countries join UK expelling Russian diplomats over spy poisoning Italy Italian President Sergio Mattarella has expelled 2 Russian diplomats. Getty Countries join UK expelling Russian diplomats over spy poisoning Canada Canadian Prime Minister Justin Trudeau has expelled 4 Russian diplomats. Getty Countries join UK expelling Russian diplomats over spy poisoning Finland Finland's President Sauli Niinisto has expelled 1 Russian diplomat. Reuters Countries join UK expelling Russian diplomats over spy poisoning Denmark Danish Prime Minister Lars Lokke Rasmussen has expelled 2 Russian diplomats. AFP/Getty Countries join UK expelling Russian diplomats over spy poisoning Romania Romania's President Klaus Werner Iohannis has expelled 1 Russian diplomat. AFP/Getty Countries join UK expelling Russian diplomats over spy poisoning Norway Norwegian Prime Minister Erna Solberg has expelled 1 Russian diplomat. REUTERS Countries join UK expelling Russian diplomats over spy poisoning Spain Spanish Prime Minister Mariano Rajoy has expelled 2 Russian diplomats. Getty Countries join UK expelling Russian diplomats over spy poisoning Sweden Sweden's Prime Minister Stefan Lofven has expelled 1 Russian diplomat. AFP/Getty Countries join UK expelling Russian diplomats over spy poisoning Albania Albanian President Ilir Meta has expelled 2 Russian diplomats. AFP/Getty Countries join UK expelling Russian diplomats over spy poisoning Australia Australian Prime Minister Malcolm Turnbull has expelled 2 Russian diplomats. Getty Countries join UK expelling Russian diplomats over spy poisoning Macedonia Macedonia President Gjorge Ivanov has expelled 1 Russian diplomat. AFP/Getty Countries join UK expelling Russian diplomats over spy poisoning Hungary President of Hungary Janos Ader has expelled 1 Russian diplomat. AFP/Getty

As for an international diplomatic role, the UK has taken no part in any of the major mediation opportunities of recent years. A nuclear North Korea may not be an immediate threat to the UK, but we have been absent, or perceived as partial, both in the war in Syria and the conflict in Ukraine. First calls are made not to London, but increasingly to Paris and Berlin. A new role as peace-broker seems not to be on the cards.

The UK looks set to be straddled awkwardly as a country too big to be a plausible intermediary, but too small to be a great power. It is worth asking, though, whether all Brexiteers will regret this. Not everyone who voted Leave did so in the hope of making Britain – or England – great again.

For some, “taking back control” meant the UK being its own master, not only in who it lets in, but in what it does outside its borders. And the appetite here was for drawing in our horns, ditching imperial nostalgia and ending ill-advised interventions.

So while it is unlikely that the UK will resemble, say, Norway – either in its future relations with the EU or in any independent path it may choose – at least for this group of Leave voters the lessons for UK diplomacy from the past month may not be too disheartening.