Few issues better illustrate the total gulf between some parts of our country and others than the question of fish. Many people on these islands live in or close to coastal communities, places where there were once thriving fishing fleets which were devastated by the Common Fisheries Policy. Many others in the same country know next to nothing about this experience, and care even less.

Remember the picture that came to sum up the out-of-touch arrogance of elements of the Remain campaign, in which Sir Bob Geldof and a variety of his supporters and hangers-on swore at fishermen who were campaigning for their industry to have a future. The gap between the experiences and opinions of the two was far wider and deeper than the waters of the Thames which divided their respective boats.

Overall, I suspect the sight of Geldof’s jeering v-sign did harm to the Remain cause, even if it amused some of those who think it fashionable to mock people in grubbier, older industries. The reason goes beyond the general unloveliness of a multi-millionaire dismissing hard-working people fighting for their jobs; British fishing may be a shadow of its former self, but there are a lot of people out there who regret its demolition, to the extent that it has become quite an iconic issue for some. The fact that the CFP meant factory ships from other countries having unrestricted access to British waters, with severe ecological effects, all under policies decided in a way that gave equal weight to member states that don’t even have a coastline, made it a very emotive issue for a sub-set of voters in the referendum, who are now watching closely to ensure we take back control of our fisheries.

It’s into those waters that the Chancellor chose to wade yesterday. Asked whether access to British fishing waters would be up for negotiation as part of a general deal with the EU, he replied:

“Fishing is an iconically important British industry and we are very clear that we are taking control of our waters. But of course we would be open to discussing with our EU partners about the appropriate arrangements for reciprocal access for our fishermen to EU waters and for EU fishermen to our waters. We would have to negotiate the basis on which such an arrangement could be fair and appropriate for us.”

Cue understandable concern from various eurosceptics and voices in the fishing industry. After all, both groups have grown used to being betrayed by Westminster in its dealings with Brussels over the last 40-odd years, so suspicion runs deep and the habit of watching closely for weasel words dies hard.

It’s a sensitive topic, which illuminates several things about Brexit more generally.

First, as Iain Martin points out, it’s a reminder that the smug declaration that “we have nothing the EU wants” which has become a tagline of certain pro-EU campaigners is absolute nonsense – they ardently want access to our consumers, our money, and our fish, among other things. Rather obviously, British territory contains a disproportionately large share of Europe’s fishing grounds, which is an asset to us and something Brussels desires.

Second, the EU’s demand in their latest negotiating document that full access for EU fishing fleets to British waters must be continued is a major hole in the supposed logic of their negotiating position. How many times have Barnier et al denounced “le cherrypick” (a delightful term which incidentally rather sinks Juncker’s claim that English is now irrelevant, but anyway)? EU principles are universal and immovable. They are indivisible. They are not something that a rules-based organisation can possibly deviate from by allowing cherrypicking. And yet here is one M. Barnier, seeking to cherrypick an agreement on fisheries on the very basis of mutual recognition and easy continuity which he claims is impossible to apply to other industries. The inconsistency is both a bit awkward for the EU, and a gift to the Prime Minister, demonstrating her argument last week that cherrypicking is the norm, not some unacceptable and alien concept.

Third, the question of the future of British fisheries allows us to plumb exactly what “take back control” really means. It was clear during the referendum, and has been reiterated by the Government since, that it means UK democratic sovereignty over laws, regulations and policies – that Parliament, or devolved assemblies, should get to wield the powers previously held by Brussels, be they on agriculture and fisheries or immigration and public spending. That obviously rules out membership of EU common policies or continued authority for the European Court of Justice, so staying in the CFP would be out of the question, but to be meaningful sovereignty surely it should also allow these regained powers to be used in ways that Eurosceptics might dislike?

In this instance, does “taking back control” mean not just regaining British democratic control of fisheries policy and law in our waters, but restricting access to British vessels only? Or could it incorporate an agreement by which we set the laws and the policies but some Spanish or French vessels were allowed to fish here under those rules, subject to British quotas and/or taxes and fees, for example in return for the EU providing access to financial markets on the same basis?

Fourth, this is an early taste of the new political territory which is going to be explored as a result of Brexit. It is more than 40 years since British voters even had the right to consider questions like this when they cast their ballot, and nobody quite knows what they will view as untouchable or on what they will accept compromise. It’s easy to see a betrayal narrative gaining ground if, rather than a restoration of the UK fishing industry, there’s a surrender which allows the old, catastrophic system to continue uninterrupted. But I wonder what would happen if Spain, a major EU fishing nation, was to drop all claims and attempts at incursion on Gibraltar in return for some degree of fisheries access – might voters view that as an acceptable trade-off?

This all foreshadows much larger and even more controversial debates yet to come, not least on immigration. Here as on fisheries, I suspect once people know they have democratic control once more, the electorate will become not unconcerned but less hardline about migration. End free movement, as people demand, and support for things like total freezes on all immigration will deflate. The question of whether leaving the Common Fisheries Policy but accepting some kind of compromise agreement on access could be an early testing ground for that new politics, and all parties would be wise to watch it closely.