Dr Lee Rotherham was Director of Special Projects at Vote Leave

Brexit does not encourage sun tans. Over the past couple of weeks, I have been digging into my Alexandrian-scaled library of EU-themed literature to work on a headline Risk Register for what renegotiation means. Even a fairly coarse whittling of the source material suggests a policy list of several hundred Chinese Puzzles that negotiators now need to play with.

This sounds like a cruel task. The cheery news is that overwhelmingly these problems turn out to be shallow shell scrapes to stumble into rather than Vietcong bamboo pits. The risk in many cases lies more in the embarrassment of failing to prep the plank. Spotting there is a transitional issue, knowing the default and whether it needs to be improved, will often prove the key activity.

Looking at that full and ranging list of Risks though, something else also becomes clear – and it should not be a Jeffersonian revelation to longstanding Eurosceptics. Leaving the EU is not an end in itself. It is a set of opportunities. Whether the UK simply transitions, or now thrives, depends on the capability, ambitions and vision of those implementing change.

I would suggest four principles may now prove critical over the medium term.

The first is that Whitehall now needs to be engaged in a joined-up revolution. Policy makers will regain access to whole shelves of tools that were previously padlocked away. This will mean many problems merit a total rethink of how cross-departmental cooperation can better deliver on strategic targets. Examples include inspiring UK productivity, opening up to innovation, increasing the appeal of the City as an international hub, rewriting the meaning of human rights in society, and redefining the democratic processes for effective regulatory oversight. Or take FDI: nineteen of the twenty commonly-identified reasons for attracting foreign investment into the UK are not Single Market-related, and new cross-departmental opportunities now emerge. Meanwhile, tackling immigration means addressing at least 26 policy areas across 10 departments, as well as engaging local government and bringing in Police and Crime Commissioners.

The second point relates to maintaining consent. The milestones have been laid towards the EU’s exit, but certain forked road decisions ought to be held back for manifesto commitments. The ‘Leave’ campaign was a coalition across all political parties. With rare exceptions, the campaign did not set out a list of guaranteed policies – Vote Leave did not after all constitute a revolutionary government – but instead highlighted many opportunities that future policy makers would become free to pursue, or not to pursue. Where there is a party-tagged choice, the big turnstile changes deserve to be signed off by the voter in a future election. Let equilibrium-changing options like careening the Social Chapter, or (for the Corbyn manifesto) renationalising the railways, now generate a national debate.

That is not to halter Brexit, merely to guarantee that the referendum mandate also provides a democratic stimulus. Another example would be with agriculture, where farm payments mechanisms could be simplified (without the European Commission, DEFRA’s IT system may even become UK-compatible!) – but a total reorganisation of subsidies deserves wider consultation, broader strategic public debate, and electoral buy-in.

In a number of policy areas though, there is already a consensus on what change means. Policy makers need not always be skipping across the untrampled pampas, but where an explored path exists they should follow the ruts of the wagon trail. ConservativeHome’s recent article on fisheries reform is a case in point. While thoughtful, provocative and useful, I would suggest it was ahead of time. The core answers to life after the CFP have already been delivered thanks to Owen Paterson, whose Green Paper was the result of direct engagement with the communities affected. Since this exploration of the aspirations of trawlermen has won long-standing support from within the industry, and underpinned the material published by Restore Britain’s Fish during the referendum campaign itself, it is logical that devolved Fisheries Management Authorities and Days at Sea should constitute policy direction – at least for now.

Such short-term caution is not to cement solutions completely, merely to deliver on expectations. We might thus also consider the specialist aspects of immigration management. The public presumption is that an “Australian-style points system” will be introduced. But on review, in some ways a Canadian system is a better option, coping with shifting job market shortages through its sliding job points rating. It even has an added exotic tassel in that the Quebec aspect could be tweaked, to allow a small special quota for Gaelic and Welsh speakers from overseas to rejuvenate their cultural ties with their ancestral homelands.

Such Canadian/Australian differences (which are borderline esoteric to most people) obviously weren’t discussed during the campaign, though the broad principle was. The point is that picking the Ottawa model would still introduce a scored quota system and deliver on voters’ expectations. By contrast, not picking any form of quota system, and – worse – not addressing migration limits at all, would represent a core breach of them.

The final point is more fundamental. Brexit allows Whitehall an opportunity to revolutionise its attitude towards governance. We can predict some departments will be much better at doing this than others. Core to this is acknowledging that the EU is not the sole guilty source of gold-plating of laws. Whitehall is more than capable of adding costs and burdens on its own, without Brussels. So ‘de-barnacling’ drafts as they pass via departmental legal advisers, for instance, will be key.

According to the answer to a Parliamentary Question in 2010, only an estimated 31 per cent of UK red tape costs in force were down to EU rules. The real figure is likely to be far higher – those interested in understanding these obscure processes can find some of the detail set out elsewhere.

Or take another audit. There is a neat symmetry in the Brexit referendum taking place when it did, ten years to the month after the Department of Trade and Industry published its Final Report of its Administrative Burdens Measurement Exercise. The DTI’s study in June 2006 reviewed administrative costs arising from laws, and broke them down into three categories – costs arising from EU or wider international rules; costs arising from the UK adding to those rules; and costs arising from rules generated solely at UK level. It calculated that nine tenths of costly legislation by volume fell into the last category, which was half of the costs by value. So while about 40 per cent of red tape by value was attributed to EU laws, Whitehall itself was proving to be a more than equally guilty partner.

Now, though, this can change. Firstly, thanks to the referendum, the UK no longer needs to obsessively gold-plate to keep on the right side of the European courts; and secondly, removal of the Commission and MEPs from the scene ends the excuse of drafters succumbing to peer pressure.

So, fresh portals have opened. Are the opportunities now before us going to be realised? Or will civil servants repatriate powers from Brussels, merely to nationalise the administrative attitudes that went with them? If the latter, Brexit has come too late to save us from our continentally-inspired decline. But it need not necessarily be so.