Is Hollande to be trusted on Brexit costs?

In case you wondered, there is no deep love or mutual admiration between the French president Francois Hollande and David Cameron.

Hollande was not doing the prime minister a personal favour by saying there would be ominous "consequences" for the UK if we were to leave the EU.

Of course it was sweet music for David Cameron that the president implied Brexit could mean the end of border controls on the French side of the Channel that act as a powerful buffer for Britain against thousands of migrants and refugees who want to come here.

But this succour provided to Cameron's campaign for Britain to remain in the EU was an act of self-preservation by the French president.

Please forgive me for stating the hideously bleeding obvious, but Hollande is a fully paid up member of an elite of left and right that has governed France continuously for well over 60 years - and whose central tenet is that there is no credible alternative to the growing convergence of European nations under the framework of the EU and its precursors.

And what's a looming disaster for Hollande - and his mainstream opponents of France's right - is that their grip on power is threatened by the large and growing popularity of the acutely nationalist Front National under Marine Le Pen.

Blond(e) political ambition is visibly evident in American, French and British politics in 2016. Credit: PA Wire

By the way, and to digress for a moment, have you noticed that the tripod of nationalist politicians of the right who are punching through in the world's richest economies are all bulky blondes or blonds whose defining characteristic is that they speak as they find - namely Le Pen, le Trump and le Boris (anyone know what odds I would get on a trifecta of each emerging as head of government in the coming three years?).

The imperative for Hollande in the face of the threat from Le Pen is the same as it is for Cameron facing BoJo: he has to characterise Le Pen as an unrealistic extremist.

It would therefore be an act of political suicide for Hollande to lend credibility to the idea that the UK could be prosperous, safe and stable outside the EU, because that would beg the question why Le Pen is wrong to suggest France too could go it alone.

The two leaders put on a united front at the Anglo-French Summit in pushing for Britain to remain in the European Union. Credit: PA Wire

Or to put it another way, there is an absolute alignment of interest between Cameron and Hollande - if on nothing else of substance - to paint Brexit as thoroughly bad for Britain.

The point is that Hollande's political future rests on making it as hard and painful as possible for the UK to leave the EU.

Which means he is not an objective judge of the costs and benefits of Brexit, except to the extent that - maddeningly for the proponents of leaving the EU - Hollande does have considerable power to maximise some of those costs for Britain.