About centre points - let me get quantitative for a minute. Identify the main issues (axes) of the political spectrum. Assume that positions can be approximately ranked linearly on each issue, and find the median voter position for each. That's the political centre. Theis may not be very meaningful if you need a lot of different, very narrow issues in order to have linear axes.
So, in the 2007 French Presidential campaign, what seem to be the two or three key issues (and this could be something like 'can we have a woman president' rather than, say economic left/right, if that's the turn the campaign takes in the voters' view), and where's the centre? "It's the statue, man, The Statue."
My point is not to deny Sarko is further right than Bayrou, or Royal further left. It is to say Bayrou is right-ist in his leanings, and historically on the right in terms of his personal tradition and political career - including the symbiosis with the Gaullistes in which he and his movement have always lived (until his decision to break off to make this run). That was the meaning of the journalist's question about the centre - are you really trying to tell us you're the centre, and not the right?
Now, the electorate may be sufficiently fooled by his posture to put him in Round Two. But political parties and personnel do not have short memories like the TV-gazing masses. They won't give him a free ride.
The truth, imo? Bayrou at the Elysée would mean he had created a new balance on the right. He would ally with the UMP again, but this time on new terms, with him as boss. I'd rather see him than Sarko in that position, but then again I'd rather see neither.
(Otherwise, I know you can produce a graphic representation of political views and thus define a "centre". I think it may be useful in a time series, to compare changes and trends. Not as anything other than an oversimplification, though, if it is meant as a description of the extremely complex dynamic system we might call history.)
You seem to be implying that there is no centre, and if there is, it's not Bayrou. "It's the statue, man, The Statue."
I think your question is really for another diary, and later on, when major issues do in fact become clearer and more clearly discussed. For the moment, it's more a war of position. There are something like sixty days to go...