One or two very welcome guests below the line at Liberal Democrat Voice have challenged us to talk more about immigration in the context of the EU referendum. Because people want the UK to “take back control of our borders”. So here we are.

Of course we do have control of our borders. We are not part of Schengen, and there is nothing they could do to make us join. We have our own immigration policy, subject, as with all policy, to treaty obligations. The specific treaty obligation of interest here is the provision in the Treaty of Rome to allow the free movement of labour between members of the EU: a right exercised by 2.2m Brits living and working elsewhere, and by 2.3m other Europeans in the UK. Brexiters may also talk about the refugee crisis, but this is just an attempt to smear by association – the treaty obligations and benefits at stake in the referendum relate to the rights of EU citizens.

Now don’t forget that it is scaremongering to question whether we will have access to the single market post-Brexit but it is worth noting that the free movement of labour also applies to Switzerland (who has only partial access to the Single Market) and to Norway, and that these two countries are often held up as examples of the sort of happy trading relationship outside the EU that might be available to us. (A relationship that also involves following the single market rules and paying into the EU budget.)

I wrote a few days ago about the game theory of post-Brexit negotiations, and it is sober reading for anyone who thinks our negotiating position would be a strong one. All I need add here, is that, while, yes, Germany wants to sell us BMWs, the other 26 including Poland and Bulgaria will have a veto on the trade deal. They do not want to, and should not, sign up to the national humiliation of a deal providing for the free movement of British goods without the free movement of Polish and Bulgarian labour.

How did we get here? We joined the EEC because it was in our interests to do so, free movement being one of the benefits. And we supported the expansion of the EU into Eastern Europe because it was in our interests to do so – to comprehensively win the cold war, to advance and entrench democratic values in our former enemies with the offer of full membership of the Western European club of nations. Some of the resistance to expansion at the time was from European federalists who rightly feared that a wider Europe would not be a deeper one, but the British view prevailed. Had it not, the events in Ukraine might be happening in Poland today, with the rest of eastern Europe under Putin’s control.

So now some want Britain to turn round and argue that it is all very well having free movement with the richer countries of western Europe, but to extend it to the east represents an intolerable loss of sovereignty. This is to wish away a foreign policy triumph for which we’d have given our right arms in the 1980s. It is to say to the East, that yes we offered you full membership, we said you could be our equals, but we didn’t mean it. Thoroughly dishonourable.

Free movement of labour across the whole EU is something to support, not just because we should keep our promises, but because it is a mutual benefit to the people of all the member states. It is not a loss of sovereignty, it is something that a responsible sovereign government signs up to for the benefit of its electors, as ours did. Freedom to trade without freedom to travel is a one-sided freedom that elevates the commercial interest above the human.

* Joe Otten was the candidate for Sheffield Heeley in June 2017 and Doncaster North in December 2019 and is a councillor in Sheffield.