On Friday, November 28, 2014 8:20:14 AM UTC-5, gareth wrote:
These LED replacements for 240V mains lamps; if one were to
open them, would one find a high voltage regulator suitable for
some of our valve experiments and repairs?

There is not a whole lot in there.
AC/DC supply, Buck/Boost controller chip with triac dimmer sensing (if it's a dimmable LED lamp), small inductors caps, rectifiers.

TI and ONSemi have controllers and reference designs at their web sites.
I don't know if the govt regulators are requiring any sort of power factor correction.

There is a whole lot of power factor correction circuitry going into higher current consumer goods in the EU so there should be good parts(inductors rectifiers, switches, caps) in a few years when consumers begin yearning for newer models.