After decades of denying that Brussels creates very much law, the ‘in’ campaign has changed its tune. 

'English common law is not affected. For a few commercial and industrial purposes there is need for community law.'

Thus an official Yes campaign flier reassures referendum voters that Brussels poses no threat to the UK’s legal cultures. Of course this was in June 1975. Four decades on, no one on either side in the Brexit debate can dispute that the acquis communautaire now spans a great deal more than ‘a few commercial and industrial purposes’.

What's interesting is the side of the debate making the noise about it. 

Until very recently, you could bet that anyone talking about the quantity of England and Wales law inspired by EU directives, created by regulations or shaped by EU Court of Justice rulings, was a thorough eurosceptic, probably of the 'betrayal' school. Hence the tedious number game about the percentage of legislation originating in Brussels rather than Westminster (or Holyrood, or Cardiff).

For its part, the pro-EU camp has always tended to play this down, for example by noting that voluminous regulations governing the production of olive oil do not have much relevance in the UK however much they are part of the law of the land. When the House of Commons Library had a bash at a definitive answer in 2010, it is notable that the higher estimates all came from opponents of EU membership. 

Last week, though, I heard the scale of the EU’s contribution to English and Welsh law advanced as an argument for staying in. A meeting of the All Party Parliamentary Group on constitutional affairs, supported by the Law Society and Bar Council, seemed to show a consensus that the extent of legal entanglement would make any divorce impracticable, at least within the two years envisaged by the Lisbon Treaty.

None of the MPs and peers present, overwhelmingly if not unanimously, from the 'in' camp, contested the point, though the ever-vigilant solicitor MP Alberto Costa cautioned about making too much of it, on the basis that supporters of Scottish independence had gone into their referendum on the promise that three centuries of British legislation could be undone in 19 months. 

Costa's point is good. There are several problems with the 'already in too deep' argument, quite apart from the risk of it being labelled a classic sunk-costs fallacy. 

For a start, it sounds defeatist. Unravelling UK and European law would be a tall order, though undoubtedly a bonanza for law firms, but it wouldn't have to be done on day one. UK legislation originating in European directives, including many important employment rights, would remain in force. The status of direct EU regulation could be tackled by a constitutional convention – 'agreeing to agree', as Gordon Nardell QC, chair of the Bar Council's EU law committee told the meeting.

(Admittedly, this first would need agreement on where the end-point should be, quite a tall order at this stage in the debate.) Regulations deemed essential for doing business with the EU, including the quixotic General Data Protection Regulation, could presumably be fast-tracked into legislation through some sort of portmanteau bill, to be re-opened down the line if and when a UK government decided it had the mandate. 

But the main problem with the 'we're in too deep' argument is that of credibility. You don't have to be a swivel-eyed little Englander to suspect that the legal sovereignty aspect of European Community and EU membership has been deliberately downplayed. It was a thorough europhile, the late Hugo Young, who stated in his 1999 history of UK-European relations This Blessed Plot, that he could trace no document from 1975 saying in plain terms that national sovereignty would be lost.

'Seldom, if ever, did the leading speakers address specifically the implications of the European Court of Justice,' he adds. This time round, the government's information campaign, with its emphasis on the UK's 'special status' is not much better, though citizens willing to wade through the near 100-page HM Government paper Rights and Obligations of European Union Membership will learn that all member states 'must adopt any legislation necessary to give effect to EU law in their national law'. 

Gazette readers, especially those who entered the profession in the quarter century since Ex Parte Factortame, will not find this a startling revelation. I suspect the wider electorate is less at ease. For evidence that the prime minister and his 'in' cabinet suspect this too, look again at the General Data Protection Regulation. Why has its arrival, with on the face of it greatly improved rights for UK citizens, not been trumpeted from Whitehall? I cannot find so much as a press release, let alone a high-profile politician's speech welcoming the regulation.

The answer, of course, is that David Cameron does not much like the measure, which is based on an assumption that the way to help Europe create the next Google is to set up a new lattice of regulation around the web. And Cameron likes even less reminding voters that he has no choice about imposing it in the UK.  

In June 1975, I don't recall thinking much about European legislation (except possibly the prospect of pubs opening in the afternoons). I was labouring night shifts in a rubber-vulcanising plant and, unlike most of my friends, voted in favour of the European Economic Community because it looked like a door to an outward-facing future. I wish I could say the same thing this time round.

Michael Cross is Gazette news editor