Thanks Jays & Stewart for replies. The Williams boss actually looks identical to this, so maybe it is to extend the wheel rather than shorten it. It is a very fine 2000 car I'm currently looking at, possibly to replace my M3W. Importantly, my wife can get in and out easily.
Tim
The one in your photo is the standard Motolita one that most dealers including Williams, stock. Williams also had a much slimmer boss made for them by motolita which is designed to bring the wheel closer to the dash and with a flange which hides the ugly gap on the later column shrouds.
