HANDS Off Our Parliament, said the banners outside Holyrood yesterday, as demonstrators formed a human chain around the building.

Many carried Yes flags and other Saltire-themed paraphernalia from 2014, but the event was explicitly billed as pro-devolution rather than pro-separation. An interesting straw in the wind, of which more later.

The spur for giving Holyrood a hug was the interminable EU Withdrawal Bill (EUWB). For the demonstrators, and most MSPs, this is a “power grab” over 24 devolved policy areas being repatriated from Brussels at Brexit. The UK Government says these need to be temporarily “ring-fenced” at Westminster, pending the creation of UK-wide common frameworks to protect the UK single market.

The Scottish and Welsh governments want the powers devolved, in line with the devolution settlement, or at the very least for the frameworks to be drawn up by “consent”. At the moment, the UK government is only offering to “consult”. If there’s no agreement, it reserves the right to create frameworks as it sees fit regardless.

Unspun: The political diary

This deadlock bore some very exotic fruit on Wednesday. Both Holyrood and the Welsh Assembly went off the constitutional map to pass alternative bills to the EUWB to deal with devolved EU law.

This was not what anyone said they wanted. All three governments insist they want to amend the EUWB by common agreement. But that continues to look a very big ask.

Knowing the potential mess ahead - a scrap in the UK Supreme Court, Westminster using its sovereignty to impose legislation - they still failed to strike a deal and are now teetering on a constitutional crisis.

The Holyrood bill was doubly contentious. It was the first time MSPs ignored the Presiding Officer’s advice and passed legislation he had warned them was ultra vires.

As Holyrood voted, the House of Lords was debating the EUWB, and many of the arguments heard at yesterday’s demo were there too.

Former Plaid Cymru leader Lord Wigley said he feared the EUWB would “normalise direct rule from Westminster”. He said it reflected a tendency “in areas where devolution may be a nuisance or a hindrance to the UK Government’s agenda, to roll back devolution, or at the very least to attenuate it, or centralise certain powers in London.”

While Labour’s Lord Hain said the “virus of Whitehall-itis”, which causes infected UK officials to instinctively resist devolution, had “crept into this Bill as well”.

Unspun: The political diary

Despite fervent hopes for a deal, and peers touting a council of the nations to thrash out frameworks as a way out of the impasse, there was little sign of harmony erupting.

Accused of mounting a power grab, the UK government’s riposte was to argue that, actually, the power grab was on the side.

Lord Keen, the Advocate General for Scotland, and a former chair of the Scottish Tories, said the EUWB was about “continuity, certainty and control” and accused SNP ministers of trying to “feed populism”.

For him, creating frameworks by consent would not respect the devolution settlement, it would extend it by giving Holyrood a veto over measures that would affect not just Scotland, but England, Wales and Northern Ireland. “I know that within some Administrations there is a determination to push for consent. Consent, as such, is constitutionally very difficult; I indulge in under-statement when I say that,” he said.

Giving one administration in one devolved nation a veto over “the interest of the other nations in the United Kingdom as a whole... is not and never was the purpose of the devolution settlement.”

Former Scotland Office minister Lord Dunlop said such a veto would “go beyond the current devolution settlements... It risks turning the Sewel convention from a political commitment into a legal obligation.”

Just after the Welsh and Scottish Brexit bills had passed, Lord Keen closed the debate by laying down the UK government position.

A unified single market within the UK would require “a body to have jurisdiction over that single market. That ultimately has to be Parliament of the United Kingdom. There is no other way of addressing that issue.”

Frameworks might yet be reached by a “collaborative process”, he said. But as for consent? Forget it.

I’m sometimes told none of this matters a damn. After all, where are the votes in whether MSPs or MPs modify retained EU law on pesticide use? But these issues seep into the public consciousness over time.

Brexit has starkly exposed the limits of Holyrood’s powers, and reminded people of Westminster’s capacity for blunt force legislation.

These are strange days for the constitution. Brexit is causing the rivets to pop out of the devolution settlement. Holyrood has thrown down the gauntlet to Westminster. MSPs have snubbed the Presiding Officer. A cross-border square-go is looming at the Supreme Court. We’re not in 1999 anymore, Toto.

Hence the SNP and the Yes movement becoming born-again defenders of old school devolution. There are no siege engines outside Holyrood as I write, but the message that our plucky parliament is under attack could well get traction.

Unspun: The political diary

I suspect the SNP will noisily stand up for devolution until the next Scottish election, then tearfully declare the fight unwinnable, and morph into its pallbearers.

You can imagine the lament. ‘We tried to save it. For 20 odd years we did our best. But devolution is broken. It is time for something new. Giving Holyrood a hug wasn’t enough, we have to liberate it.’

For now, the EUWB and its spin-offs are largely the preserve of the anorak community. But they will be distilled and pumped into a wider narrative to sell independence. They certainly do nothing for the Union.