In the Telegraph last week, Andrew Roberts suggested that one of ‘the many splendid opportunities provided by the … heroic Brexit vote’ was the chance for Canada, Australia, New Zealand and the United Kingdom to unite as a federation. Nigel Farage advised Irish radio listeners to ‘hedge their bets’ by rejoining the Commonwealth. And Liam Fox (who wants us to abandon our ‘obsession’ with Europe in favour of the Commonwealth) has started ‘scoping out the parameters’ of a free trade deal with Australia.

Rekindling our colonial heritage may be all the rage among right-wingers, but it’s still just idiosyncratic chatter. Roberts has been a credulous cheerleader for powerful people for years – at least since February 2003 when, as the UK hesitated over war, he compared Tony Blair to Churchill and predicted his ‘apotheosis’ after ‘hundreds of weapons of mass destruction are unearthed from where they have been hidden’. Many patriots would meanwhile oppose any kind of federation that allowed free movement: Farage, though keen nowadays to portray the Commonwealth as a diverse alternative to the EU, also idolises Enoch Powell, whose racist reputation was built on the vilification of Commonwealth Asian and ‘Negro’ immigrants to Britain. Any hope of building a post-imperial bloc is correspondingly chimerical, and Australia’s government has said that bilateral negotiations can’t even begin until the UK has definitively fixed its future trading relationship with the EU.

It’s tempting to imagine that Theresa May realises this. She seems to be a pragmatist, and any effort to restructure Britain’s economy on resuscitated colonial links would be the bet of an unusually careless gambler. But May does like to surprise as well, and in her first speech as prime minister, she channelled the political spirit of Joseph Chamberlain, one of the earliest champions of an Imperial Federation. That earned favourable coverage from journalists who like the idea of May as maverick, and she could invite more comparisons by focusing on trade with the Commonwealth; London will be hosting its biennial summit in spring 2018 (postponed and relocated from Vanuatu because of the damage caused by Cyclone Pam last year).

Assuming she’s reluctant to go too far down this avenue, however, there is a random factor that could upset her calculations. The wild card is Boris Johnson. The foreign secretary shares the prime minister’s admiration for Chamberlain – though he probably sympathises less with Radical Joe’s politics than the looseness of his loyalties (he was a Liberal mayor of Birmingham and Conservative colonial secretary) – and, with dutiful nods at Churchill, he frequently expresses his support for closer union with the world’s ‘English-speaking peoples'. That doesn’t imply admiration for the Commonwealth – which Johnson once suggested exists primarily to supply the queen ‘with regular cheering crowds of flag-waving piccaninnies’ – but his lip service is now bound to become more respectful. And the niceties of diplomacy may dovetail with self-interest.

For the time being, Johnson owes Theresa May his political life, but as negotiations with Brussels grind on and she makes inevitable concessions, the tables are going to turn. All he’d need then to re-emerge as Brexist-in-Chief is a pseudo-manifesto, and free trade with ex-colonies would fit the bill perfectly. Its hint of imperial revival would allow him to pander to nostalgia and racism without saying an illiberal word – a trick he has been perfecting for months, anyway – while leaving him well placed to take May down, as and when her political credit finally goes bad.

That’s just speculation (except by comparison to the Brexiteers’ own prognostications, which make it look like quantum mechanics) and the guesswork may be awry. Perhaps ministers are about to abandon the fantasies and buckle down to the question of whether we should stay in the single market. The foreign secretary might forego celebrations of Anglo-Saxon genius and push for actual reform of less nebulous imperial legacies – the mandatory hanging laws that disfigure the statute books of Malaysia, Singapore and Trinidad, for example, or the British-based penalties against homosexuality that still exist in three-quarters of the countries London once ruled. There’s time enough. The Commonwealth Heads of Government Meeting isn’t convening for 18 months. Brexit won’t literally mean Brexit until 2019, at the earliest. And once that’s all done, it’ll be easier to look sensibly at plans to revive the British Empire.