Whilst on holiday I received this in an email from the dealer supplying my GTD:
03 October 2013
Make sure customers are aware that callipers are plain grey
VW1209-13
Golf GTD brake callipers do not have the GTD logo on, as incorrectly stated in the brochure and price list.
This is a misprint. An updated price list and brochure are being worked on and will be available on Desktop shortly
So the answer is that they don't even though the brochure states otherwise...
On a positive note my build has been confirmed for w/c 3/11/2013 - which is a week earlier than expected...