First Minister Carwyn Jones fears UK break-up
First Minister Carwyn Jones fears the break up of the UK within 10 years because of the UK Government's response to fall-out of the Scottish "No" vote.
Mr Jones accused the prime minister of "tinkering" around the edges.
"If we don't heed the lesson from Scotland we won't have a UK in years to come" he told Week In Week Out.
Meanwhile, an ICM Research/BBC poll found 60% in Wales would like to see policing devolved and 56% some welfare benefits.
Mr Jones spoke of his frustration at the UK Government wanting the issue of future powers across the UK being dealt with by a Cabinet sub-committee rather than a convention where all UK devolved governments were sat around a table.
"If they don't get this right in future - you can see the Scots coming back, being unhappy.
"In order to avoid all this and to keep UK together we need to have proper constitution for next centuries to come and work out where powers will be.
"If that isn't done my great fear will be that in 10 years time in Scotland we'll be back with another referendum and the result may well be different. That's the lesson the establishment need to learn."
The ICM poll commissioned by BBC Wales suggests support for the Welsh government to decide how much income tax is paid in Wales.
The survey found 46% in favour and 37% against the idea.
The first minister has insisted that the so-called underfunding of Wales needs to be addressed before income tax powers are devolved.
Wales receives money from Westminster relative to its population through the Barnett formula.
But politicians claim this is over-generous to Scotland and Wales receives £300m a year less than it should do.
Mr Jones has already called at the Labour conference for a "new UK" with the strong identities of its nations "recognised within a common bond of solidarity".
On tax devolution, economist Gerry Holtham tells tonight's Week In Week Out programme he thinks that ministers in Cardiff Bay have been reluctant to embrace tax-raising powers because of "fear".
Mr Jones denied this saying there was no point taking on tax-raising powers before the funding has been sorted out.
In the poll, voters were also asked whether Welsh MPs should be prevented from voting at Westminster on matters that only effect England.
A total of 44% agreed but 41% disagreed - suggesting Prime Minister David Cameron's bid to introduce so-called English votes for English laws has divided opinion.
ICM Research interviewed a random sample of 1,006 Welsh adults aged 18 or over by telephone on 19-22nd September 2014. Interviews were conducted across Wales and the results have been weighted to the profile of all adults. ICM is a member of the British Polling Council and abides by its rules.
There is more on this story on Week In Week Out on BBC One Wales at 22:35 BST on Wednesday 24 September.