The most damaging element of Lord Lawson's intervention on Europe in today's Times is not so much his decision that the facts have changed and that he would vote to leave the European Union in a post-2015 referendum, but his lack of faith in David Cameron's ability to secure any notable reforms. He writes:
'We have been here before. He is following faithfully in the footsteps of Harold Wilson almost 40 years ago. The changes that Wilson was able to negotiate were so trivial that I doubt if anyone today can remember what they were. But he was able to secure a 2-1 majority for the 'in' vote in the 1975 referendum.
'I have no doubt that any changes that Mr Cameron - or, for that matter, Ed Miliband - is able to secure will be equally inconsequential.'
Cameron is well aware of the dangers of over-promising, which is why, although he has started talks on renegotiation with other European leaders, he hasn't offered a 'shopping list' of the changes that he wants. To do so would be to set himself up for failure as pundits and members of his own party could judge him to have secured only five out of his 10 aims. Better to pretend that any concessions are a big victory and represent everything he ever wanted, even if, as Lawson argues today, they are inconsequential.
But there is one aspect of Lawson's argument that is in a way helpful to the Prime Minister. The last thing Britain needs as it approaches a renegotiation is to give the impression that it will stay in the EU even if it secures some very paltry reforms that no-one notices, let alone remembers. So a growing impression that the political class is gearing up for an exit unless EU leaders offer something spectacular will strengthen Cameron's hand. The question is whether he's able to give that threatening impression as effectively, when he's already been quite clear that he'd much prefer Britain to remain an EU member state.