As soon as I get my hands on them they will be painted up as Brits, this guy is straight out of Osprey and works for me, right number of buttons or not.
If 'this guy' is straight out of the Barthorp/McBridge 'Marlborough's Army' title (plate D) then he is an Austrian Cuirassier circa 1705, with a grey coat and dark red facings. British cavalry of the WoSS looked nothing much like this. So painting these figures as WoSS British would be a little like painting Zulu Wars British Infantry as British Infantry at Omdurman....something quite different.
However, you may be thinking of painting these as English cavalry of the Restoration (Charles II) era, in which case much better: replace any tricornes with broad-brimmed felt hats and you're on to a winner!