newshound explained :
Whatever, I guess I need a new megger, any views on the £30 Chinese models
from eBay, or should I be looking at a second hand Avo / Robin / Fluke etc?
This is not for "professional" use, it probably only comes out a couple of
times a year.

I bought one years ago, unlikely the same model, but it did 1,000, 500
and 250v, with a low voltage resistance test, plus LCD display. I
checked the voltage droop under load and I must say it proved to be
quite well speced for holding up its voltage and accurately calibrated.