Cutting a dejected and browbeaten figure in front of the ultimate symbol of political power in the UK, Theresa May delivered one of the most significant and emotional speeches of her tenure as prime minister on Friday.

It is perhaps a sign of the times in Britain that the oration in question was her letter of resignation.

In the speech, she expressed her regret that she had not delivered Brexit and further stressed the need for compromise to deliver what has (thus far) been undeliverable.

A clear way forward out of the current Brexit deadlock is unlikely to be forthcoming for her successor. But what is certain, the election of the next leader of the Conservative Party and prime minister will almost certainly put wind in the sails of the Scottish independence movement.

While some may empathise with the callous fashion in which she has been harried from office by her cabinet, her party and the rightwing media, few tears will be shed for the end of her disastrous premiership, one of the shortest in the post-war era.

Those in favour of retaining the Union shouldn’t be too hasty in celebrating Theresa May’s political demise, however, for what comes in her wake is arguably more harmful to the future prospects of the country – and a catalyst for the breakup of Britain. If the Westminster rumour mill is to be believed, the current favourite to become leader is Boris Johnson.

Largely in over her head solving Brexit, May had inadvertently managed to act as a bulwark against any rise in support of Scottish independence (with polls maintaining the similar levels of support since the vote in 2014). She resisted calls for a second independence vote and was rewarded with a clutch of Scottish MPs in the 2017 general election. However, events in the last week have put pay to all that and Johnson’s elevation to prime minister will be prove to be the final, devastating crack in the dam holding back momentum towards independence.

Popular with rank and file Tories, Johnson is a divisive figure amongst the British electorate, in no small part because of his unseemly pursuit of power at all costs. Having aborted a bid for the Conservative leadership following David Cameron’s resignation in 2016, he has bided his time, using his column in the Daily Telegraph to soften the ground for a Johnson premiership while also stalking a wounded Theresa May.

“Any lurch towards a disastrous ‘no-deal Brexit’… by arch-Brexiteer Johnson would now throw moderate No voters like myself into the bosom of independence campaigners.”

A leader of the Leave campaign, he famously switched support from the Remain camp when it became politically expedient for him to do so. Having been so cynical previously, his plans on how to deliver Brexit must be treated as such, too. After all, Johnson wasted no time, after announcing he would run for the leadership, to say publically that a ‘no deal Brexit’ is back on the table and that he would be willing to let Britain slide out of the EU on 31 October without a deal in place.

In the wake of the European election results on Monday morning, it is certain that any new Conservative leader will now take a more hardline approach to Brexit, which could, of course, mean crashing out of the EU without a deal in place.

Nigel Farage’s Brexit Party, which came top of the poll with 32%, campaigned for a hard Brexit on WTO rules, wooing away Conservative members and voters in the process. Emboldened by victory, it will be hard for any of May’s potential successors to ignore the wishes of Brexit Party supporters should they wish to remain long in Downing Street.

This jars with the picture elsewhere in the UK, for instance in Scotland. The SNP – a pro-Europe and pro-Scottish independence party – enjoyed their best ever European election results. They campaigned on doing everything they could to stop Brexit or, at the very least, limit the damage of a soft Brexit. The results mirror in some regard the EU referendum in 2016 in which Scots voted overwhelmingly to Remain.

There is no direct correlation between support for Europe and support for independence (a substantial wedge of SNP supporters voted to Leave three years ago, for example) but the tectonic plates are starting to shift in this direction the longer Brexit uncertainty drags on.

While Scotland voted convincingly against independence in 2014, the spectre of another poll on the thorny constitutional issue has never been fully exorcised. Having been promised that the UK’s place in Europe would be protected by a vote against independence, any lurch towards a disastrous ‘no-deal Brexit’ (now being dubbed a ‘clean Brexit’ by populists like Farage in an effort to sanitise the danger) by arch-Brexiteer Johnson would now throw moderate No voters like myself into the bosom of independence campaigners.

True, Scottish independence would not be the sunlit uplands that Brexit was promised to be, either. And while the independence movement’s talking points – ‘no one votes Tory in Scotland’ and ‘Scotland doesn’t get the governments it votes for at Westminster’ – are a little threadbare and demonstrably untrue, there is something to be said of the UK government pursuing a damaging policy in the knowledge that Scotland and Northern Ireland are wholly against it. And still are, according to the European election results.

With the waters still muddied from May’s imminent departure, it is unclear just how the Brexit saga will end and what the fallout will be when it does. Any new leader of the Conservative Party must be conscious of the task in front of them. They will need to walk a tightrope between delivering Brexit and keeping the country together. Is the break-up of the 300-year-old Union – as unionists, something they are pledged to uphold and protect – a price worth paying to leave the EU? Sadly, I suspect Boris Johnson would make a Faustian bargain to reach Number 10.