Anybody any design ideas for a high-voltage generator for an electric fence
to deter (not kill - that's illegal in the UK) badgers from entering my
garden and digging up the lawns?

I've toyed with adapting either a boiler/gas oven ignition system or a car
ignition system ...? But I'm lost as to determining what would be safe and
how to measure the voltage (kV), current (mA) and energy (Joules) available.

Any ideas or experience welcome...
-Roy-
(Surrey, England)