Theresa May's deputy has insisted the Union is under greater strain than at any time in living memory.

Cabinet Office minister David Lidington, the de facto deputy prime minister, said an English mood of indifference to Scotland's place in the UK had added to the pressure.

It came as he argued Jeremy Hunt would be better suited than Boris Johnson to become the next Prime Minister.

Speaking to journalists at a Law Society of Scotland conference to mark 20 years of devolution, Mr Lidington said a no-deal Brexit would harm support for the Union.

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He said: “I do think the Union is under more pressure than I've known previously in my lifetime.

"I believe that the value of the Union to every one of the four nations is enormous.

“I think that we are much stronger on the world stage working together as a United Kingdom, and I think that we are significantly stronger economically as one United Kingdom.

“I think that fragmentation of the UK would diminish all four nations. Each of the four nations enriches the whole.

“I am a very strong Unionist, but I think we need to be alive to the fact that there is a combination of nationalist feeling on the one hand and indifference towards or ignorance of the value of the Union the on the other that puts that achievement at risk.”

Mr Lidington insisted Mr Hunt is "better equipped" to deal with national security threats than his rival, as well as being better placed to strengthen Scotland's place in the UK.

Earlier, the Cabinet Office minister told delegates he was shocked by a recent poll which found 63 per cent of Tory members would accept Scotland leaving the UK if it meant securing Brexit.

He added: "It doesn't accord with my own experience of talking to party members in my own constituency or in other constituencies around the country that I have visited.

"I sit with [Scottish Tory leader] Ruth Davidson on this, at the core of being a Conservative is that you believe in the union of the United Kingdom.

"That to me is something that is more important than almost any other political consideration.

"So my view is that the splintering of the United Kingdom would be harmful to every part of the United Kingdom.

"Each of us would be diminished economically and in terms of global influence and global opportunity and therefore I feel it is the duty of the next prime minister to do all in his power to uphold and strengthen the integrity of the United Kingdom and to win public support for that.

"To my mind the challenge is not simply from a strong constituency of support for separatism in Scotland or from pressure from a change of demographic in Northern Ireland.

"It is in part from an English mood that is sometimes indifferent to the union and unaware that it is the union, the efforts of the United Kingdom as a whole, that can achieve far more than England on its own."