When I had my Tomb Raider 90, I'm pretty sure that the sales literature said the the roof mounted spots are for off-road use only. So having roof mounted spots isn't illegal but using them on the road is.
(But, perhaps supporting the "folk law" comment, note that I said "pretty sure"
)
See, it even entered sales literature
If they are wired in as spots i.e Additional/ Optional main beam, so they turn on and off with the main beam switch, there are no regulations for height, or longitudinal position.
See Schedule 5, Part I of the The Road Vehicles Lighting Regulations 1989
Legislation
