Today's announcement by David Cameron and Nick Clegg that Wales will, despite Whitehall's sclerotic decision-making and coalition manoeuvrings, be offered new tax and borrowing powers has lifted the mood of Scottish and English devolutionists.

One leading proponent of English devolution, Labour MP Graham Allen was quick to seize the moment by again pressing on Friday morning for English councils to be given greater financial powers.

In Scotland, Blair McDougall, chief executive of the anti-independence Better Together umbrella campaign, took delight in getting a dig in on Twitter against the SNP MPs and officials, such as Kevin Pringle.

They had seized on the stalling and criticisms within the pro-UK parties as proof that devolution within the UK is too uncertain and unreliable to trust, so McDougall tweeted this:

When you watch devolution announcement in Wales today spare a thought for these folks. #indyref #shotfox pic.twitter.com/8h4Nr5cCct — Blair McDougall (@blairmcdougall) November 1, 2013

Allen, chairman of the Commons select committee on political and constitutional reform, said this bolstered his committee's case for English councils to directly share in income tax raised in their areas:

This Friday's welcome announcement by the PM and DPM on Wales means it is inevitable that devolution will come to England too,it is now just a matter of the form and timing. People in England are just as capable of running their affairs and English local government presents a ready made vehicle for English devolution and for Income tax assignment .No change in rates of income tax or equalisation or collection is required, but greater transparency and accountability of income tax assignment is the key to devolution.

Cameron and Clegg are now offering Wales new tax and spending powers quite closely aligned to those given to Scotland after the Calman commission: new powers to set income tax rates, new borrowing powers and devolution of stamp duty and landfill tax.

In a joint article for the Western Mail, the duo said:

For too long, decisions about Wales's future have been directed by bureaucrats hundreds of miles away in Westminster – and it has suffered as a result. Wales could benefit hugely if the government at Cardiff Bay was responsible for raising more of the money it spends.

While the borrowing powers will allow the Welsh assembly to raise £1bn for upgrading the M4 motorway, there is still a hurdle to overcome on income tax: Cameron and Clegg, as part of the deal-making with Welsh Labour, want to put that to a referendum (the third recently in Wales on devolution, excluding the vote in 1979).

It remains to be seen how that referendum will play out: will it be controlled by the Welsh assembly? And will Carwyn Jones, the Welsh Labour first minister and historically deeply sceptical about income tax powers, try to push this off? His recent softer rhetoric suggests not.

And the Welsh income tax powers, proposed last year by the Silk Commission, will have significant implications for Scotland. If passed by a future referendum, Cardiff Bay's powers will be greater than Holyrood's on income tax and that will chafe.

Wales will be able to set variable rates across most or all tax bands: Scotland's powers are heavily circumscribed, because Holyrood must raise or lower all the main tax bands by the same amount – it has no flexibility at present to cut lower rates and rise higher rates. For many devolutionists, this makes it a clumsy fiscal tool.

(It is worth noting, however, the Institute for Fiscal Studies said earlier this week that since Scotland has comparatively fewer higher rate tax payers and fewer zero-rate tax payers, the impact of varying tax bands on Holyrood's overall tax income may be modest.)

But the key thing here, say analysts and devolution campaigners, is that the Cameron-Clegg agreement establishes that enhanced devolution is now embedded in the constitutional reform agenda, within both the previously hostile Conservative party and the one equally resistant higher echelons of Whitehall.

Alan Trench, the devolution expert and adviser to various Welsh and Scottish devolution commissions and working groups, says:

This is a much broader shift towards a fiscally decentralised as well as policy decentralised UK. What we're starting to see is an increasingly diversified UK, but there's still questions about how much real political control lies at English local level.

Trench believes the Welsh powers deal is a victory for the Lib Dems within the coalition, who have overcome resistance from David Jones, the sceptical Tory Secretary of State for Wales. It has been pushed steadily but quietly inside Westminster by Danny Alexander, the chief secretary to the Treasury and Clegg's Lib Dem deputy in government. And Clegg's deputy chief of staff is a former Welsh Lib Dem chief executive, Jo Foster.

Says Trench:

this is, to a significant degree, a win for the Liberal Democrats rather than the Conservatives. The Lib Dems have been wanting to take away from Labour the monopoly on writing the Welsh constitution which Labour has had since 1999. And the second thing is that they had committed themselves at a very early stage to a Calman outcome for Wales.

Willie Rennie, the Scottish Lib Dem leader, was fast to capitalise on that, arguing:

This is proof that the scare stories from the nationalists are wrong. The nationalists' negative anthems which say devolution will be upturned if people vote to stay in the UK are being proved wrong month after month. This is evidence of change across and within the UK, and it's happening now. Scottish Liberal Democrats are proud to have led the debate in Scotland with Ming Campbell's report last year. We will continue to build our case for a stronger Scotland within the UK.

As too was Alistair Carmichael, the Lib Dem Secretary of State for Scotland, who insisted that the UK parties actually delivered on devolution time and again:

This is now the second occasion on which the Coalition Government has delivered on promises for extra powers to the Welsh Assembly and we've also delivered more substantial powers to the Scottish Parliament through the Scotland Act. This is proof that when we say we will deliver powers that we do it.

Nonetheless, there are senior Welsh Tories who have been pushing the enhanced devolution agenda vigorously, including former party leader Nick Bourne, who sat on the Silk Commission, David Melding, deputy presiding officer in Cardiff Bay, and others – this is something overlooked in Scottish politics.

Cameron has, perhaps more for strategic than ideological reasons, has decided to embrace the concept of devolution more than others in his cabinet, including Jones, might like. He has put his handprint on today's announcement quite deliberately.

Trench asserts "the Welsh Conservatives have actually been some of the best thinkers about the union."

And David Mundell, Carmichael's Tory deputy at the Scotland Office, weighed in:

Devolution is safe in this government's hands. We believe in providing more powers to different parts of the UK while retaining the many benefits we all get from being part of a strong UK. We are delivering devolution while independence would deliver the end for devolution.

This raises interesting challenges and opportunities for both Labour and the SNP.

As its internal deliberations on greater devolution through Johann Lamont's commission slowly trundles on, the Welsh measures raise the bar and the political temperature on Scottish devolution too. Lamont is promising a more far-reaching model, involving decentralisation within Scotland as well as to Scotland.

Trench said Graham Allen's proposals have little support. But this could well strengthen the hand of Labour's devolutionist wing over its conservatives, and also see at UK level Labour thinkers like John Cruddas, the MP for Rainham and Dagenham, and the English devolutionist John Denham, MP for Southampton, Itchen, start pushing out a more holistic model for pan-UK reform.

And so it implies too that defeat for Alex Salmond at next year's independence referendum would mean the silver medal option of greater fiscal and law-making powers for Holyrood is now increasingly possible.

Salmond is instinctively a gradualist. And Trench believes that were Wales to endorse and implement proposals for variable rates of Welsh income tax, it is near inevitable that similar powers to enhance Scotland's autonomy over tax powers would be given to Holyrood too in any post-no vote devolution settlement.

And Wales's "devolution journey" is still not over: the Silk commission is still to report next spring on increasing the assembly's legal and policy-making powers, while the Northern Irish too are mulling over greater devolution.

This raises a more subtle question too, which the Lib Dems and Better Together should consider: how much might Welsh devolution help Salmond make the case next year that his increasingly light independence proposition in the referendum – where Scotland shares a great deal with the UK within a re-imagined union of the nations - is actually the most intelligence evolution of devolution of them all?

So what this Welsh development actually suggests is that Labour, the Tories and Lib Dems are now on under greater pressure - self-imposed given today's triumphant rhetoric - to offer Scotland's voters a tangible, concrete alternative model before September 18.