AS the linchpin legislation for Brexit was published on Thursday, Scottish Secretary David Mundell was trying to enlighten the media about its contents. Sitting with lobby journalists in Dover House and with a video relay to the Scottish press pack in Edinburgh, Mr Mundell’s best moment was his first, a half-knowing Freudian slip. Before the briefing began, he said he would let officials take any “technical” questions. Technical, he said, meant “hard”. The European Union (Withdrawal) Bill is certainly hard, and Mr Mundell is no technical whizz. 

Despite the hoo-ha around it, the Bill is essentially mechanical. Its purpose is to repeal the European Communities Act of 1972 that took the UK into Europe; to bring the body of EU law into UK law; and to empower the government to correct thousands of laws which will no longer make sense after Brexit with minimal fuss. The latter, also called a Henry VIII power, will last two years after Brexit in March 2019. Meanwhile, the big post-Brexit policy changes on agriculture, immigration and other areas will be the subject of a raft of separate bills.

Incidentally, the correcting power confirms the Tories have no intention of allowing a second independence referendum before the next Holyrood election. Their manifesto said it would not be before the Brexit process had “played out”. The two-year timetable for corrections makes that at least spring 2021.

Mr Mundell said the Bill would bring about a "powers bonanza" for Holyrood. But Nicola Sturgeon and Carwyn Jones, the Labour First Minister of Wales, instantly trashed it as a “naked power-grab”. Far from delivering a rush of new powers, it would impose new restrictions on what their respective parliaments could do. True, or just the tiresome “process row” predicted by Mr Mundell?

At issue are Section 11 and Schedules 2 and 3 of the Bill, which amend the powers of the devolved parliaments and the ministers in the devolved governments. At Brexit, EU law will be transferred into UK law, becoming “retained EU law”. The UK government says broadly the same systems will apply before and after Brexit, to ensure continuity of the statute book. After the UK leaves the EU, Holyrood will therefore have the same powers and restrictions as it did before Brexit. Sort of.

Right now, the Scottish Parliament cannot legislate in a way that is “incompatible with EU law”. But after the Brexit, it will not be allowed to legislate on retained EU law full stop, even in devolved areas, except to correct deficiencies in the broken bits. Instead, Westminster will have a near monopoly over retained EU law. It will be reserved by default. In the jargon of the Bill, there will be a limit on devolved “competence”. One reason is to preserve the UK single market. It would be make little sense for Holyrood to create a unique food labelling system, for example, given the burden on business. But instead of trusting Holyrood to act wisely, MSPs will be denied access to the realm of retained EU law - at least to start with.

The Westminster power hog is meant to be transitional, a stop-gap while the UK and the devolved governments discuss which powers should be transferred to Edinburgh, Cardiff and Belfast, and which shared across the UK in lasting “common frameworks”. Rather than a bonanza of new powers, there will be a drip-drip as the limit on devolved competence is lifted here and there, and new powers trickle north out of Westminster. Holyrood will see a net increase in its powers, but the scale and timing are unknown.

As Colin Imrie, EU policy analyst at Strathclyde University’s International Public Policy Institute, put it: “Whether this will enhance or diminish the Scottish Parliament is a matter of opinion, but such a change has profound implications for the governance of Scotland.”

In his briefing, Mr Mundell also said there would be no change to Schedule 5 of the 1998 Scotland Act, one of devolution’s sacred texts. This lists powers reserved to Westminster, with the result all else is devolved by default. However the UK government’s explanatory notes to the Bill don’t say that.

Instead, it's clear the government hasn’t put all its cards on the table yet. Paragraph 195 states: “Not all changes to the devolution legislation have been included in the Bill on introduction. For example, changes to the list of reserved matters in Part 2 of Schedule 5 to the Scotland Act 1998. This is because the UK Government intends to discuss these changes with the devolved administrations before finalising the amendments.” In other words, the reserved powers are in play, and Holyrood better watch out.

As Mr Mundell would say, a lot of this is “hard”. Brexit is a migraine bonanza. But behind the familiar political bickering, devolution is headed for deep change, and we should all pay attention.