On balance, have we benefited from being in the EU?

“What have the Romans ever done for us?” the Monty Python team famously asked – the implication being that the many benefits, from sanitation to peace, were being taken for granted. Would it be fair, then, to ask in the same spirit: “What has the Treaty of Rome and the European Union ever done for us, the British?”

It is a fair question, but very difficult to answer.

Obviously, there is no parallel universe where the UK did not join the then European Communities in 1973, or where the British did not pioneer the single market of 1992, or, for that matter, where the EU didn’t launch its troublesome single currency in 2000; or where it did launch the euro and the UK joined it at some point.

Presumably, the UK would have remained in the European Free Trade area, or EFTA, like Norway (which rejected EU membership in a 1972 referendum), and thus been in the European Economic Area, and would anyway have been affected, for good or ill, by EU rules. Or maybe not.

It is, then, at base, a counterfactual argument, or else one that rests on assumptions about the future of the UK after Brexit. All of this is hazardous.

Still, some brave souls have attempted it, and there is some degree of consensus. Overall, the short answer is that the range of estimates of the purely economic costs and benefits of EU membership vary from minus 10 per cent to plus 20 per cent of British national income. Most of what seem to be the more authoritative surveys are in a range of minus 1.5 per cent to plus 9.5 per cent of GDP today. Thus, the UK is probably anything from £30bn a year worse off to £200bn a year better off as a result of being in the EU.

Or, to make it more relatable, anything from costing each household £1,000 a year to benefiting it by £7,500, through a variety of higher private living standards and better public services than would otherwise have prevailed. A wide range, then, but sufficient to get some scale into the debate.

There is also a surprising amount of agreement on the way different “channels” have affected the economy – though not on their relative importance or scale.

Thus, on the negative side comes: the net financial contribution to the EU budget; the cost to business of poorly designed EU regulations; the amount EU external tariffs add to UK import prices; the depressing effects of ERM membership in 1990 to 1992; the negative impact of the eurozone crises of the 2010s; and the initial impact of the “cold shower” on UK employment, prices and growth in the first decade or so of membership.

The positives are generally considered to outweigh the negatives – though much of the argument remains hypothetical and most of the relevant figures are difficult to measure. They are also very difficult to disentangle from other big economic trends, including broader globalisation and the rise of China, the “Thatcherism” reforms of the 1980s (labour market, privatisation, liberalising the City), as well as (non EU) immigration. Smaller factors, such as operational independence for the Bank of England or the “austerity” policies after 2010 have also had an impact.

In summary, the economic benefits are: access to the largest single market in the world, which implies greater economies of scale for firms operating in it, lower costs to consumers, more competitive costs for business of inputs from capital to labour and raw materials; the lion’s share of foreign direct investment to the EU because of that single market access (the symbol being the Nissan car factory in Sunderland, founded in 1986); participation in the globalised supply chains of UK/EU-based companies; zero tariffs and quotas on goods and services moving in and out of the UK/EU; the spur to competitiveness for British business after 1973 (with winners, such as finance, and losers, such as fishing); and the way migration has helped employers better match skills and vacancies, both skilled and unskilled.

Outside the EU, it is argued that we can trade on World Trade Organisation (WTO) rules, which is correct, and it is also true that WTO supervised tariffs are far lower than they were in 1973. Against that, there is some doubt as to the future effectiveness of the WTO in an increasingly protectionist world.

Some assumptions also have to be made about how the EU’s most recent mega bloc deals with Japan, Canada and South Korea will pan out compared to hypothetical future ones between the UK and those nations (as well as the likes of the US and India). Over time, patterns of trade can change, and economies do adjust, and much of the future growth of the world economy will take place outside the mature economy of the EU. For now, though, the EU is the UK’s biggest trade and investment partner.

Of course, this is purely about economics, and money isn’t everything. There is also the, possibly apocryphal, example of the Leave supporter who tweeted that they would rather lose their job than stay in the EU. The question “What have the Romans ever done for us?” was, after all, posed by members of a politically-motivated group, the People’s Front of Judea, who seemed to place economic considerations secondary to the question of sovereignty. No value is easily attached to that.

Got an unanswered question about Brexit? Send it to editor@independent.co.uk and we’ll do our best to supply an answer in our Brexit Explained series.