Just a heads-up to fellow deprived UK residents: a lot of P60 drop ins have appeared on Amazon UK recently, and the prices seem reasonable also. (But be prepared for some searching, because they pop up in all different departments.)
There are coloured ones, including a 5-mode 90 lumen red drop-in, and also a single mode 150 lumen (claimed) red drop in.
Many of them sold by Lightscastle. Who they? Anyhow, given the low prices I have ordered some to see what happens.
I'll reply to my own post now I've received the items to let other UK people know.
First the good news: all three drop-ins I ordered arrived in good time and well before the Amazon-stated delivery date of 11 April. Direct from China.
All work, in that they light up. After this it gets more negative.
The 800+ lumen white P60, well that output is a wild exaggeration IMHO. I've no instrumentation to actually measure it, but I would put it nearer 200 lumen by comparison with other lights I own. For example, it is noticeably less bright than my 320 lumen Olight.
The 150 lumen red P60 is hardly brighter than the 90 lumen one, plus it seems more orange than red. (This one was not Lightscastle BTW).
The 5-mode red P60 only has one mode, and output identical to the red drop in I already own (90 lumen). Maybe someone can advise on this: do I need anything else to get the modes to work? It is in a Ultrafire 501.