Legacywr, if you are unsure about white silver & it is a dealbreaker. I would look on Autotrader for white VW's for sale and try to find one specifally in WS at a dealership nearer to you, rather than travelling up to London.
It is a marmite colour and rare on a GTi, I have seen a couple of WS 7.5 GTi's over the years and a few more R.
One good thing is exclusivity, I doubt you would ever park next to another WS 7.5 GTi with a pan roof & 19" Santiagos, even at GTi international?
