In recent years, it’s been part of the job description for the occupant of Dover House to keep a relatively low profile.

Being Scottish Secretary is a thankless task. When it’s going well, the dull clank of constitutional gears rarely captures the public imagination. Since devolution — and particularly since the SNP came to power at Holyrood and the independence referendum — headlines involving the Scottish Secretary have rarely meant the UK Government is ‘winning the day’ in media terms. It seems a sad reflection on the office held by Donald Dewar and Tom Johnson, but no news has generally meant good news at the Scotland Office. It is the unhappy fate of the current Scottish Secretary, however, to live in interesting times.

David Mundell’s nickname does him a bit of a disservice. In person, he lives up to his ‘fluffy’ tag as a gentle, genial person, but he is political fighter and survivor. He stood lonely watch over the Tories’ only Scottish outpost for 12 years and through four general elections, narrowly hanging on to his Dumfriesshire, Clydesdale and Tweeddale seat in 2015 when others were inflating expectations.

David Mundell, the Scottish Secretary, has been under pressure over claims of a Westminster 'power grab' (Picture: Getty)

As the only Scottish Conservative MP, he not only had to put up with panda jokes, but also had to wait his turn to lead a department that he might have been entitled to expect, instead serving under Lib Dem secretaries of state during the coalition.

‘Fluffy’ Mundell is more teflon don than teddy bear. He’s the second-longest serving member of cabinet in their current role. He has served under two Prime Ministers, helped deliver two Scotland Acts and seen off an independence referendum.

David Mundell '˜confident' of Scottish Brexit '˜power grab' changes

Brexit, however, could see the fluff start to come out at the seams. For Mundell has gotten himself into that most awkward of places for a Scottish Secretary: the headlines. First there was the deal with the DUP that kept Theresa May in power. Mundell said he was “not going to agree to anything that could be construed as back-door funding to Northern Ireland”, but that is exactly what opponents claim the £1bn for Northern Ireland was. It took some hard spinning get him out of trouble.

Now it is the vexed matter of which new powers Scotland will get after Brexit, and how the UK Government intends to deliver them. Once again, Mundell’s own promises came back to haunt him after he said the EU Withdrawal Bill at the centre of the current ‘power grab’ row would be amended before it left the Commons.

It wasn’t, and Mundell has good cause to be annoyed at Damian Green’s Cabinet Office for the delay, but the promise was his. He is, remember, no longer the lone Scot on the Tory benches, and his colleagues weren’t impressed at having to face opposition taunts and leaflets, either.

As mitigation, Mundell said the delay would ensure that “the changes we bring forward will command support on all sides”. But that now looks unlikely.

It has been clear for weeks that Whitehall’s attitude towards its devolution dilemma has changed. As The Scotsman revealed last month, the intention on Whitehall is to keep talking in search of a deal with Edinburgh and Cardiff — but if one isn’t forthcoming, it will push on regardless.

They don’t have much choice. Deadlines have come and gone, and the parliamentary lives are just about used up. The Lords have to pass the Withdrawal Bill before the summer recess, and the government’s legislative timetable is built around the assumption that they can get it done by June. There is still a window to tweak the amendment the government put down yesterday, but it isn’t particularly wide, and neither side seems particularly keen to hurl themselves through it.

Behind the scenes, talk from UK Government sources has grown more and more bullish. Gone is the language that got Mundell into his current bind, suggesting the Withdrawal Bill would only proceed with the consent of Holyrood and Cardiff Bay. It has been replaced with suggestions that Edinburgh has overplayed its hand, that London could win a game of constitutional chicken, and that the SNP’s case will collapse in the court of public opinion. “They aren’t going to have a fight over fertiliser regulations, are they?” is the incredulous joke repeated in recent weeks. Crucially, the Scottish Tory backbenchers appear to be on board.

The problem with that strategy is that London started out by saying there was nothing to see here — just that same, dull clanking of constitutional gears — only to ramp up the rhetoric about protecting the UK’s internal market when it looked like a deal wasn’t possible.

Assuming that ordinary people wouldn’t ever notice or care about the powers returning from Brussels was always risky. These are issues that we haven’t had to think about while we were in the EU, but the widespread opposition to the now-defunct TTIP trade deal with the US shows enough people care about them to make life awkward for any government. On the list of powers subject to a ‘freeze’ at Westminster are rules governing public procurement and farm subsidies, while other powers that have now been drawn into the row include benefits for migrants and aspects of state aid.

These are not fertiliser regulations or food labelling standards, and it isn’t sustainable for a government to shout about taking back control only to whisper that the things it is taking control of don’t actually matter that much.

All of which means the chance of a breakthrough when Nicola Sturgeon meets Theresa May in Downing Street tomorrow is slim. The First Minister won’t march out of Number 10 demanding a second independence referendum — she tried that one to her cost in 2016 — but unless the UK Government can tidy this up by the time the Withdrawal Bill leaves the Lords, it risks adding fuel to the campaign for one.

If it arrives, Mundell could yet again find his own words repeated back to him in big, bold newsprint. It won’t be a comfortable experience.

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