The Barnett formula for allocating public money to Scotland needs to change, according to the man in charge of a review of the devolution settlement.

Sir Kenneth Calman said all the evidence received by his commission called for changes to the system, which was created more than 30 years ago.

Asked if the formula should be reformed to better reflect a needs-based system, he said: "I think all the evidence we've had, and I speak mainly about the evidence coming in, suggests that needs to change."

He said the current system can leave "gaps" and added: "The issue of changing that, in whatever way I don't know, is clearly one of the big tasks."

Sir Kenneth stressed: "I don't know the answer. It is quite important that we have not, repeat not, come to any conclusions at this stage at all."

His observations prompted an aide to the First Minister last night to claim that the only acceptable alternative to Barnett was for Holyrood to have full financial powers of its own and complete control of Scotland's resources.

Calman was established by the opposition parties at Holyrood as a counterpoint to the government's "National Conversation" process leading to an independence referendum.

The Calman Commission now heads south to take evidence in London and Newcastle to understand how people in England perceive devolution and the Barnett formula.

On the perception of the Scottish Parliament, he added: "I think it would be fair to say that one of the conclusions that we'll come to is that the Scottish Parliament is working quite well.

"There's strong support for it from pretty much everybody who's written in and devolution has been a positive benefit to Scotland. That's quite important."

But he said the general public still do not fully understand the responsibilities of devolved government.

"It's been working quite well, so people say well, let's just get on with it'," he said.

Sir Kenneth said only one profession, accountancy, had expressed a wish for some responsibilities to return to London.

The commission is due to convene in London on November 5 and 18 then Newcastle on November 19. "We thought going there will give us an interesting bit of evidence in relation to how Scotland's perceived and how things like the Barnett formula is perceived," said Sir Kenneth.

Asked if the formula was fair to English taxpayers, he said: "It depends where you live in England. It's important you don't think of England as a single place.

"You can break down the regions quite easily. If you look at London for example, you would see London does pretty well."

The Confederation of British Industry, chambers of commerce and NHS are expected to be involved in the sessions and Lord Turner is expected at the London meeting. Further Scottish venues will include Dundee, Stornoway and Ayr.

A report is due to be published by the end of this year outlining the main themes of the commission's work.

An aide to Alex Salmond said last night: "The only acceptable alternative to Barnett is full fiscal autonomy for Scotland and control of our own resources."

He added that this year's Government Revenue and Expenditure in Scotland report "put it beyond doubt that Scotland is subsidising the rest of the UK - and that the flow of resources is from Scotland to the London Treasury, not the other way round".

He added: "City accountants Grant Thornton estimate that Scotland is currently subsidising the UK Exchequer to the tune of £4.4bn. This gives the Scottish Government a powerful platform to press the case for action and justice now on the vital energy issues facing our nation."