Image caption Tony Blair said renegotiation with the EU was a "refuge" for those who wanted the UK to leave it

Tony Blair spoke to the pro-EU Business for New Europe' group, but his intended audience was far wider.

The venue was Chatham House but - unusually for the frank meetings which take place in this plush pile in London's St James's - his comments were attributable and on the record. So his warnings to David Cameron, Ed Miliband and EU leaders were veiled. Albeit thinly.

His main quibble with the current set of European leaders was that, amid the austerity, very little thought was being given to making the positive case for the EU.

He warned that influence and power would drift from West to East unless Europe was united and member states co-operated even more closely on trade, energy and the environment.

But his rhetoric ratcheted up a gear when he talked of the UK's place in Europe.

He sounded genuinely unsettled when he said that - on his global travels - he was increasingly asked if the UK would leave the EU.

Although he said he was always emphatic in answering "no", he recognised that "the case for Britain leaving is now made openly by members of the governing party and far more widely supported amongst the public at large".

'Thick of things'

He felt that Euroscepticism was spreading "like a virus" and, using the kind of jive talk you might have expected to hear when he was still a member of the pop combo Ugly Rumours at university, he pronounced: "The Right have got it bad on this Europe thing."

In more statesmanlike tones he warned that leaving the EU would be "hugely destructive of Britain's interests", and he argued - as did Labour leader Ed Miliband in his recent CBI speech - that "our country faces a real and present danger in edging towards the exit".

Mr Blair refused to accept invitations from his audience to denounce David Cameron personally but, in advance of the current prime minister's much-anticipated speech on the EU, this former PM got his retaliation in first.

He did not limit his criticisms to those who openly wish to sever links with Brussels.

Instead, Mr Blair characterised those, such as Mr Cameron, who argue for a change in the UK's relationship with the EU as really being in favour of withdrawal.

He said renegotiation was "a refuge for those who want to leave"; he criticised those who would rather be "semi-detached" than "in the thick of things"; and warned that eurozone countries who were "in an existential battle to survive" would neither welcome an attempt to rewrite the rules, "nor accommodate it".

Mr Blair was also less than enthusiastic about political positions struck by some in his own party.

'Dramatic consequences'

He praised Mr Miliband's call to forge alliances in the EU to bring about reforms, but when asked to comment on Labour's demand for a cut in the EU budget, and support from some senior figures for a referendum on EU membership, he gave what he described as a "diplomatic" answer.

He restricted his comments to urging the opposition to be "very careful" in its handling of the European issue and stating that he was "sceptical" that a vote on membership would be sensible at the moment.

Mr Blair added that he saw little merit in "an in/out referendum in the abstract".

Elsewhere in his speech, he said the "toughest challenge in politics is resolving the tension between the best long-term policy and the best short-term politics".

There were two noteworthy admissions from an avowed supporter of the EU. First, Britain could survive the process of withdrawal.

It would not, he argued, be "wise" and the UK could lose its global leadership role, but that it was as important for Europhiles not to over-exaggerate the dangers, just as it was vital that Eurosceptics did not underestimate the consequences.

'Snake oil'

Second, he was not bullish about the prospects for the single currency. He said he "hoped" the eurozone would not break up, and there would be "dramatic consequences" if it did - but he did not rule it out.

Mr Blair said he was making this speech so that the counter-argument to those who saw withdrawal from the EU as inevitable could be put. His entourage made it clear this was not part of a campaign to take a big job in Europe.

However, a small band of protesters steeped in satire stood outside calling for him to be a directly elected EU President because of what they referred to as his "integrity" and the "euro's strength".

The question is what weight the former prime minister carries with his party and the wider public.

UK Independence Party leader Nigel Farage believes his influence will be negligible.

His assessment was that Mr Blair, "like his promises", was past their "use-by date" and that voters would not listen to a man who put "snake oil rather than milk on his cornflakes".