Most racegear outlets are near the circuits, well away from London. However I suggest you try Grand Prix Racewear in Chiswick. http://www.grandprixracewear.com/

This is about 20 mins west of central London by cab, I think Gunnersbury is the nearest tube station.

HTH

SS7

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Carrara white pauper's 2.7
Snickers wrapper in the door bin
Flies on the number plate
Church's scuffs on the kickplate
'Goodwood' umbrella in the back