A TORY minister made a joke about Mhairi Black’s recent marriage in a quip about the Union while deflecting criticisms that the UK is “holding Scotland back”.

The comment came as the SNP’s Scotland spokesperson in Westminster asked the UK Government to explain why “independent countries, similar to Scotland are wealthier, more productive, have higher social mobility, have lower poverty levels, smaller gender pay gap and lower inequality”.

Iain Stewart, the Tories’ under-secretary of state for Scotland, said: “Before I answer the honourable gentle – honourable lady’s question, may I just congratulate her on her recent wedding?

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“And although we will disagree on many subjects, on this one I hope we can agree that a union is better than independence?”

The quip was met with good humour from Black, who was shown laughing in response.

She swiped back: “I welcome his warm words, but I would like to remind him that unions have to be voluntary.”

The minister added: “On the substance of her question, this Union has been one of the most productive in history.

“Only the separatists could believe that a hard border between Scotland and England, with 60% of Scotland’s exports are to the rest of the United Kingdom, only the separatists could believe that creating such a hard border would be in our economic and social interests.”

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Stewart was met with jeers when he suggested the Union was “voluntary” – a key question in the light of the First Minister’s announcement of a date for indyref2 in Holyrood yesterday.

Black also asked: "The leader of the Scottish Conservatives has actually changed his view on the Prime Minister three times in six months - so why then does this Government refuse to let people in Scotland change their view after eight years?"

Nicola Sturgeon told MSPs a referendum would be held on October19, 2023, if the Scottish Government’s new independence referendum bill is approved by the UK.

But if it is not, it will be the “fault of Westminster legislation” and give the lie to the claim the Union is a “voluntary partnership”, Sturgeon added.

Scottish Secretary Alister Jack was absent for the exchange because of “longstanding engagements in Scotland”, according to Stewart.

The UK Government has again insisted "now is not the time" for a second referendum in response to the First Minister's announcement 

Black was married to her partner Katie at a ceremony in Glasgow on June 12.