The way I see it, Europe is the unfinished business of the 1980s.
By 1990, there was an emerging Thatcherite critique of the EU. The EU was led by a social democrat (Delors) and was seen from Britain as having a corporatist strategy for development. IE if the unions were on board and there was a social compromise, society was at peace and you could get on with building up the European economy as you wanted. As far as the people who led the EU were concerned the condition for avoiding war or civil war was still (as it had been in the 1940s, 1950s and 1960s) social compromise. The Thatcherites disagreed with them.
To the Thatcherites, the unions were so weak – in the EU and in Europe – that you no longer to make a deal with them. Corporatism was based on a false calculation of the weakness of the global ruling class and they wanted a period of ideological attack against the “enemy within” (trade unions, overpaid workers, peace campaigners, feminists, LGBT groups…). To put it in its crudest form: the rich were fed up with paying taxes and no longer understood why “their” politicians expected them to pay anything.
There was also a secondary aspect to this with the Thatcherites saying Britain could trade with the US and Japan rather than the EU – but that was the second, weaker part of the argument. More UK businesses had stronger links then (and today) with the EU than the US and this wasn’t a strong enough basis to create a majority for departure. Plans for changing Britain, rather than geography of trade, were key.
By 1990 (when she was toppled) Thatcher herself was sounding more and more like she was in favour of the UK leaving the EU but it didn’t happen, because Thatcher as an administrator was more cautious than she was as an ideologue and she tended not to do the things she said she would do until she was convinced that they were guaranteed not to rebound on her – the Conservative Party in Parliament was more ideologically heterogeneous then than it is now so she did not have a majority to push EU departure through – and the poll tax was coming and her authority was diminishing and Europe was one of the factors that made her seem week.
Since the 1980s the EU has become more important:
i) In the period where Social Democrats were in government in most EU states (c1995-c2008) they pushed legislation through the EU institutions (the working time directive, the equality directive, etc). The EU didn’t stop being a caucus for organising business or capitalism but it’s style looked too social democratic to the Thatcherites. While many on the left have used this period to say the EU was too neo-liberal, as far as the Thatcherites were concerned it wasn’t remotely neo-liberal enough.
ii) the EU’s reform period has placed more of a burden on small businesses for whom the EU personifies the cost of hiring labour in a world of employment tribunals, health and safety laws… There is a burden for big business too, but it is swallowed up by the larger scale on which larger companies operate. Hence the hard brexit supporters you hear on the radio complaining that they can’t recruit apprentices (ie workers paid less than the minimum wage) because of the (fictitious) EU taxes on hairdryers, etc.
iii) Since 2008, the EU has adopted politics of austerity which has effectively ended the period of EU reforms, and since then EU has become a driver of austerity. Obviously this is happening really fastest in Greece because of the debts but it’s happening almost everywhere (except, as it happens, the UK – where we have reached a purely national route to austerity – one reason why the social basis for a left brexit perspective is missing).
iv) Immigration has given the Tory right a populist excuse for what remains an ideological critique of the EU – that it is still too corporatist and this inhibits capital accumulation in the UK. Hence the “anti-migration” opposition to the EU of individuals like Johnson and Goldsmith who are in other ways pro-movement. As far as the Brexiter Tories, as a group, are concerned: while immigration is *not* the basis of the Thatcherite critique it could be the policy that delivers a majority for No. There will be a price to this: if they win Brexit then there will have to be significant anti-migrant moves, as the price for winning they extra 10-20% of votes they need. (We shouldn’t expect the Brexiters to move for the immediate removal of all EU migrants, but neither will they allow them to remain in the UK on equal terms to UK nationals: access to benefits, the NHS, will all come into play).
v) the Euro: Thatcherites hate it, and it has become a totem of the EU’s corporatism (Ironically, of course, in Ireland, Greece, etc it feels like the opposite, an instrument of neoliberalism).
But despite all these changes to the EU, essentially the politics haven’t moved and this is still about the unfinished business of Thatcherism rather than a critique of the EU in the last 30 years.
For the Tory right it’s about closing that period with a final victory – it’s their triumph that follows the tears they had to shed at Thatcher’s funeral.
The reason why Osborne and Cameron and the minority of Tory MPs who go along with them (it’s a very definite minority if you only count backbenchers, ie people whose jobs in the govt aren’t at risk if they call publicly for exit) do not share this belief is that as far as they’re concerned it’s too risky. Brexit would lead to a series of negotiations they couldn’t control with a horribly tight timescale (in theory just 2 years – compare the more than five it has taken to close off trade negotiations with Canada). Brexit could be bad for the City of London, uncertainty usually is. As far as the Thatcherite stayers concerned, they’ve already won in Britain – and, since 2008, in Europe – and they don’t need the extra risk.
The divide is about how much risk is needed, or not, to entrench a Thatcherite hegemony.