Just an update on this. The wife's been using the unit but having to wait for it to 'warm up' for 5-10 mins before it'd fire up so it'd gone to the back of my mind. However today I found an old adaptor which belonged to a large DAB radio which broke a few years ago. I'd kept it because I thought it might come in handy and so it did.
It's actually rated at 9v 1000ma but it seems to do the trick perfectly and is a lot heavier/more robust than the original. Switching between the 2 adaptors, I can't hear or see any difference in how the epilator operates either in speed or direction of head rotation. A brief test on my forearm left me in no doubt that it's working very well indeed...
I'm sure most people would have just chucked the epilator and adaptor away a bought a new one (c. £70) but I hate throwing potentially useful stuff away and this is why.
Cheers for the advice guys.