In a conference which has so far been pretty light on major cut-through moments, Douglas Ross’s speech to (from?) the Scottish Conservative fringe (if you missed it, catch it here) stands out.

Rather than simply focusing his fire on the Scottish National Party, the new Tory leader opens with a blunt message for Tory colleagues south of the border: shape up on the Union, or ship out.

Too many Conservatives, he says, have either given up on the United Kingdom or are even antipathetic to it, saying that: “Many, including some who govern our country, want to see a UK government focused on England.”

Where is this message directed? His deployment of the charge of ‘English nationalism’, a well-worn Remainer trope, has some thinking it could be a shot across the bows of Dominic Cummings and those conducting the negotiations with the EU. Leaving with a deal, in this few, might help to win back some of those former ‘No’ voters who have switched to independence in the aftermath of the 2016 vote.

Yet others are sceptical about the Brexit aspect of this argument, arguing that the detail of it simply doesn’t have the cut through in Edinburgh and Glasgow that politicians and commentators based in London might expect. If the Scottish Nationalists can’t even get traction for their latest grievance campaign against the Internal Market Bill, this argument runs, its not likely that a crucial slice of the electorate is waiting avidly to hear from David Frost.

Instead, Ross’s speech was about waking the Government, and indeed the wider Party, up to just how serious the situation in Scotland has become. Whilst out-and-out ‘English nationalists’ may still be relatively rare creatures, at least amongst the upper echelons of the parliamentary party, complacency is a much more serious problem. Even Tory MPs who are well-disposed to the Union are often not aware of the scale of the challenge.

Fortunately for Ross, the lack of interest he attacks is far from universal. On the parliamentary side, the newly-launched Union Research Group suggests that there remains a strong current of goodwill towards the Union amongst Tory MPs. On the grassroots side, there may soon be a new Friends of the Union group, and independent outfit Conservative Progress recently gathered senior figures from the voluntary party for the launch of their own ‘Love our Union’ campaign.

But these efforts can’t compensate for a lack of direction from the top. The Prime Minister has at his disposal the whole machinery of Her Majesty’s Government, not to mention that of the national Conservative Party and the Tory donors’ address book. Boris Johnson might not have come into politics to fight for the Union – any more than did May to deliver Brexit – but it is the challenge which now confronts him and will, if he loses, define his premiership.

If some of his senior lieutenants don’t place much personal value on the future of the UK, he must impress on them in the strongest terms that it is his personal priority – and, therefore, theirs too.