British Prime Minister David Cameron is flying to Scotland amid reports he and his close colleagues are unhappy with the anti-independence campaign.

The PM will spend two days campaigning for a “No” vote in September’s referendum, when Scots will be asked whether they want to remain in the UK.

The “Better Together” campaign is being led by Labour MP Alistair Darling, the former Chancellor.

But the Prime Minister is said to be unhappy with his performance amid polls which have shown a steady rise in numbers supporting Scottish independence, although they remain in the minority.

Mr Alistair Darling has strenuously denied suggestions he is being sidelined.

PM Cameron kicked off his Scottish trip by invoking the memory of the late Labour leader John Smith.

Speaking ahead of his arrival in Glasgow, he said: “I have been heartened to see so many people finding their voice.

“People from all walks of life and all parts of the UK know, as I know, that we are all better together.

“Twenty years ago this week, the Labour leader John Smith died. Whatever people thought of his policies, nobody could argue that he was a proud Scot who wanted the best for his country.

“And why not? Like millions of other people, he knew that loving your country and at the same time wanting to be part of something bigger does not make you any less Scottish.

“That truth is shared by millions of others. So my message is simple. We want Scotland to stay.

“We are all enriched by being together. Scotland puts the great into Great Britain. Together we are a United Kingdom with a united future.”

A Conservative Prime Minister aligning himself with a key architect of devolution will surprise some who recall determined Tory opposition to a Scottish Parliament.

There is campaigning sense, however, for a Prime Minister with a low popularity rating north of the border to reach for an association with a Scottish political icon – to seek approval by proxy.

The delivery of devolution and its benefits has become a more prominent theme in the “No” campaign in recent weeks as it endeavours to present a more positive message.

It has been criticised for conducting a negative campaign based on dark warnings about the dangers of independence, although “Better Together” insists it is merely asking pertinent, important questions.

Mr Darling said: “Any political party in government should not be afraid of the fact that, from time to time, there will be criticism and legitimate questions.

“Whether it’s me, whether it’s Standard Life, whether it’s the banks, whether it’s Barrhead Travel – anyone who says: ‘Excuse me, I don’t believe you, I’ve got a question’, gets shouted down and subject to unacceptable abuse.”

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