Best practice for this light?

[securespark]

Don't want to contradict, just offer best advice!

Still not said whether the fitting is F marked or not, though!!!

 

[The Jeep]

Your good advice is appreciated, securespark!
I'll check tomorrow to see if there's an F. Don't think so, though: it's just a standard off-the-shelf Zone 2 light fitting.
(It could be said that the regs are there so you can avoid too much scientific speculation and just do it the way they say. But sometimes other ways are just as good, but you have to be able to back up your decision).