The TLC catalog

http://www.tlc-direct.co.uk/Products/QLFRD50W.html

shows (lower middle of page) only 4 LV Halogen lamps as suitable for
LV fire rated downlighters - ie compliant with the latest Bld Reg.

Apparently the lamps need to be dichroic, with an Al reflector and a
clear flat front lens so that heat & light are reflected forwards.

Is it correct that these are the only options?

A Web search brought up Philips Masterline ES Energy Saver & Osram
Decostar 51 Energy Saver dichroic, but neither appears to hold itself
out as being for fire rated downlighters.

TIA for any experiences.