I thought they weren’t standard 
Roof looks amazing by the way, its a good variation on a common theme, I like it lots 
I’m very impressed myself turned out better than I expected
most of the black mini’s i’ve seen have gone with a checked roof
or other style because the proper union jack does not seem to
fit with in with the black & white mini’s.
Others were for Silver/grey roofs not white but when I stumbled on
this one on Ebay I took the gamble.
Really wanted this as well but a no goer 
http://cgi.ebay.co.uk/Leather-interior-classic-mini-recaro-front-seats_W0QQitemZ4630867100QQcategoryZ43122QQrdZ1QQcmdZViewItem