Thanks. I think you mean 1.57 (1.54 & 1.55 relate to interior lighting).10.6.2 (electricians guide to part p)
external lighting includes lights in porches, but not lighting in garages or carports.
When providing external lighting, reasonable provisions should be made to enable effective control and/or the use of efficent lamps. A way of showing compliance when providing external lighting would be to install systems that:
a) automatically extinguish when there is enough daylight, and when not required at night and/or
b) have lamp holders that can only be used with lamps having an efficacy greater that 40 lumens per circuit-watt (such as flureescent or compact lamp types)
PS. Ignore page 21 direction, for some strange reason my copy is different to the online one linked to
http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADL1_2002.pdf
regulation 1.54 and 1.55 page 17/18
... but where does the 120W limit we've heard about (or, indeed, any other absolute limit) come from? - this document you're referencing seems only to mention the 40 lumens/watt criterion, seemingly with no power ceiling. Indeed, 120W of CFL would be an awful lot of light ... and what about multiple lamps, which doesn't seem to be addressed in this document, either?
Kind Regards, John.