here we go, havent got time to go through it now but the statutory instruments are here:
http://www.opsi.gov.uk/si/si1989/Uksi_19891796_en_1.htm#tcon
Its real send you to sleep stuff unless you need it. Once you dig into the statutory
guidance and related legeslation ie the sub and assoc parts you'll find all sorts of info relating to the e mark and what that means for colour brightness etc of the lights.
I only recall this not because I'm an anorak (well maybe :augie ) but I've had to look through it and ,it may have been repealed, there definitely was a thing in there saying that dipped beam should be a minimum of 30 watts on a post 1986 road going vehicle (kills off the argument when someone's on the motorway on side lights only, I believe theyre below 30watts) .........................amazing the crap you remember