Brexit will monopolise the work of the executive until 2020 – and well after.  Most voters don’t follow what happens in Westminster and Whitehall, but last year’s EU referendum, and its aftermath, has left many with a sense of how sweeping the change will be.  There is an entirely new department, DexEU, whose existence is admittedly temporary, but will none the less be with us for a good while yet.  Another invention, the Department of International Trade, is more permanent.

But there is much more to Brexit than dismantling and reassembling the Whitehall lego.  All departments will be affected by the effects of leaving the EU, whether that in question is the Treasury, mulling its future freedoms in relation to VAT; or Work and Pensions, with its coming flexibilities over benefits for migrants and others; or International Development, which will no longer be required to channel funds through EU budgets, or any of them by the repatriation of procurement policy. As we write, Theresa May is en route to Cardiff, opening her mini-tour of the devolved governments, and will be probed, among much else, about which returning powers will be held at what level: how much and what sort of devolution will there be?

The most spectacular example of all is perhaps to be found at Defra, where Andrea Leadsom will be peering ahead towards independence day.  Richard Ali posed some prominent questions recently on this site: “do we want a New Zealand model of little or no support or a Norwegian model of high levels of support designed to keep farmers on the land?” he wrote.  “Do we want lower or higher levels of state regulation?  Do we want to pursue a policy of international trade or one of autarky?  What sort of countryside do we want to see, and who should pay?”  One might reverse Lord Denning, and say that Brexit is like an incoming tide. It flows into the estuaries and up the rivers. It cannot be held back.

But while voters have a rough sense of the implications of Brexit for the executive; they probably have less of its coming effect on the legislature.

Many will have heard of the Great Repeal Bill, the purpose of which is the opposite of what its name suggests – in other words, not to abolish the sway of EU law in Britain, but to reinforce it.  The Government’s logic is that this is necessary as a temporary measure.  It is intended, as the Prime Minister has put it, to give “maximum certainty as we leave the European Union.  The same rules and laws will apply to them after Brexit as they did before.  Any changes in the law will have to be subject to full scrutiny and proper Parliamentary debate”.  Getting this measure through Parliament will be a tougher proposition than passing the recent Article 50 Bill.  MPs will be tempted to try to unpick bits of EU law that they and others particularly dislike.  The ball of twine that is the Bill risks coming apart.

At any rate, the Bill will keep MPs busy.  Then there is the question of measures other than the European Communities Act that enshrine the primacy of EU law.  Furthermore, Brexit will need other Bills before we actually leave the EU.  Yesterday’s Sunday Express had a useful list for starters.  There will be at least seven of them: the paper listed measures affect migrant benefits, reciprocal healthcare, road freight, nuclear safety, emissions trading and the transfer of spending from EU funds to Government departments.  One Minister suggested that there could be as many as 15.  “Other areas would include agriculture, tax, trade and customs, fisheries, data protection and sanctions”, the paper reported.

In short, Conservative MPs have a mass of voting to look forward to – including, of course, on a mass of Henry VIII clauses integral to the repeal bill.  The Tudor monarch is about to experience his biggest revival since Wolf Hall.  All well and good, you might well say: that’s what they’re there for.  And you would be right.  MPs will be trooping through the lobbies long and late into the night.  Yes, that includes you, George Osborne!

All this will have at least three consequences.  The first is that even more lobbyists will make their way to Westminster than previously, rather in the spirit of those grizzled prospectors of old panning for gold in the southern Appalachians, in anticipation of powers returning to Parliament.  David Cameron once warned that lobbying is “the next big scandal waiting to happen”.  He may have been out by only a few years.

The second is obvious.  However long and late Parliament sits, there is only so many hours in a day.  Time allocated to Brexit-related Bills will, on the whole, be time not allocated to others.  May is going to have to scale back her plans for legislation.  She has already been doing so for some time.  Cameron was forced to retreat in the Commons over Sunday trading, academisation, disability benefits, tax credits – and more.  The Prime Minister prefers White and Green papers to trail the way, most notably on housing.

The final point arises from the Budget’s NICs cock-up.  Even a small backbench revolt can play havoc with the Government’s plans.  And there is more than a handful of Tory MPs who bear May no particular goodwill.  The Prime Minister doesn’t want this Parliament to be defined by Brexit.  But she has little choice.  This being so, she might as well make a virtue of necessity and relate as much as possible to the biggest change of course Britain has taken since it joined the Common Market, endorsed by the biggest-ever electoral mandate.

If the matter to hand is her grammar school plans, for example, she and other Ministers should relate it to the need to improve our education system as we prepare for the challenge of Brexit.  If it is her proposal to simplify technical qualifications, this should be applied to the challenge of improving skills at a time of rapid change.  If it is her quest to improve productivity, this again should be set in the context of Britain’s new challenges.  This context was underplayed in the Budget – as it has been elsewhere.