Hmmm... not one hundred percent sure, but the green and yellow epaulettes and shako cords would definitely seem to indicate a voltiegeur, or member of the light company of a line regiment.
As to the striking white coat, that jogs something in my memory about French units being briefly issued with white tunics as an ecomony measure in the mid-1800s or so. Following a quick scan of my reference shelf, below is the appropriate excerpt from Napoloen's Line Infantry & Artillery Recreated in Colour Photographs, by Europa Militaria.
"A decree of April 1806 ordered a reversion to white - the old Bourbon colour - for French Army uniforms. This was probably an economy decision, as the cost of the indigo dye used to create "French blue" had rocketed due to the effect of the British blockade on French ports. The Line regiments were divided into blocks of eight each issued with the same facing colour; the 17e to 24e wore scarlet.
In practice only a minority of regiments received white coats before the order was countermanded in May 1807. It was smart for parades, but in bivouac and on campaign it became filthy: 'All the conscripts coming from France were clothed in the white uniform, which made a really unsightly mixture when they were put in units still wearing blue. It was a really odd idea to give white uniforms to troops destined to spend their time in bivouac; you should have seen how dirty those recruits got!'. In action, 'The appearence of blood on the white coats made even the most trifling wounds loom serious'.
In November 1809 Suchet noted: 'The medley is over - there are no more hats [bicorns], no more white coats' " (p. 24)
As said, that's just a guess at what the figure could represent. It would be interesting to hear from anyone who was at the show as to whether or not Andy gave the figure a specific title?
Molloy.