Sir Kenneth Calman, the former chief medical officer of both Scotland and England, is to chair the independent review of the Scottish Parliament's devolved powers.

He was announced this morning at a press conference at which he was flanked by Scottish Tory Annabel Goldie, Labour leader Wendy Alexander and Lib Dem Nicol Stephen.

He said that the group sees independence as "not an issue" for them to address, and said his committee's independence would mean the Prime Minister would not be able to dictate its findings. After a dispute over the title of the group, it was confirmed by Prime Minister Gordon Brown this morning that he is describing it as a "Commission". Until yesterday, he and other Whitehall ministers had insisted on describing it as a review or working group, but the commission title was confirmed when the UK Cabinet approved the initiative this morning.

Other members of the group are to be appointed within the next week or so, including representatives of the three parties taking part.

They are to produce an interim report within about six months, and then consider the timetable for producing their full report.

Sir Kenneth grew up in Glasgow and became professor of cancer medicine at Glasgow University before becoming chief medical officer in Scotland and later for England. He was chairman of the executive group of the World Health Organisation and is now chancellor of the University of Glasgow. He said at the press conference: "I see myself as part of the United Kingdom, and as a Scot within that".

Tomorrow, First Minister and SNP leader Alex Salmond sets out his plans for the second stage of his National Conversation on independence.

The Prime Minister has begun a vital week for constitutional reform, with a pledge that the review of Holyrood's powers will be wide-ranging. It is to allow for all issues to be addressed including the case for more financial levers, while staying within the UK.

In an article published today aimed at English readers, he says the Union reflects self-interest for all the nations within "the world's most successful multi-national state", but it is more than "a contract of convenience that can be renegotiated".

In the Commons today, Justice Secretary Jack Straw will set out a statement of values that defines British citizenship, with the case for a bill of citizens' rights and obligations. He is also reported to be considering reform of the Westminster voting system to make it more proportional.

The next stage of constitutional reform will be to press for more power at local, regional and national levels, including stronger city government in England.

Mr Brown has renewed his attack on Scottish nationalism arguing that to be pro-Scottish, you must be anti-Union.

"The Union is a multiplier for good that too often and for too long has been taken for granted," the Prime Minister wrote for the Daily Telegraph. "It is time now to explain how the Union can benefit all of us and not at the expense of each other."

In separate developments on home rule, Labour, Conservative and LibDem leaders at Holyrood today unveil the convener of the panel that is to review devolution powers 10 years on. In an unusual move, this was being co-ordinated by the Scotland Office, even though no UK ministers are expected at today's event.

It gave the SNP more opportunity to taunt Labour for what Nationalists see as Downing Street controlling the devolution review. It was claimed the title of a review, and not a commission, as proposed by Wendy Alexander, Labour's leader at Holyrood, shows her plan has been "killed off". Western Isles SNP MSP Alasdair Allan turned up the pressure on Ms Alexander ahead of her crucial conference in Aviemore this weekend.

"The commission is dead," he said. "After four months Wendy's plans have been formally downgraded. There are now serious questions to be asked: how can the commission, meant to be a body of the Scottish Parliament, be announced as a review by the Scotland Office?

"And do the Liberal Democrats, accused by Wendy Alexander of woolly thinking', now accept Gordon Brown's edict that powers can be transferred from Scotland to Westminster?"

The raised tensions are partly explained by Alex Salmond's speech tomorrow to representatives of civic Scotland, intended to push the debate about independence out to non-political groups. The first stage of the National Conversation was launched in August, and has been conducted largely online.

The new phase has won the backing of Labour's former first minister, Henry McLeish, saying independence should be seen as "a positive option". Sam Galbraith, his former ministerial colleague, responded that it would be better for Labour and for Mr McLeish if he joined the SNP.

Labour yesterday claimed the SNP's National Conversation is "a sham and a desperate attempt to cobble together superficial legitimacy for independence at taxpayers' expense". Front bencher Jackie Baillie hit out at "inflammatory" comments which have been posted on the Scottish Government's website, including the suggestion that all Union flags should be burned, and an attack on English retirees living in Scotland. She said: "They can't disguise the fact that it is being met with complete indifference by the Scottish people."