http://www.osborneandcollins.co.uk/walton-surrey/Inspection-Testing-Electrical-Installations.htm
This is what is proposed. Slightly more than you state. Please note the reference in table 3 to Caravans.
A little research can go a long way.
My original statement with regard to what I said should be needed was based simply on the word "caravan".
Now as I am sure you will be fully aware, a caravan can be anything from an 8' shed to a 40' static.
The weekend sheds aren't going to need much in the way of a test/inspect because they have bugger all to start with, however some of those 40' jobbies have an installation that would rival bricks & mortar.
I personally couldn't give a monkeys crotchpiece whether dodgy caravan electrics result in someone's death or not, and I also think (or rather, know) that the proposed fixed fee of £80 isn't going to entice many qualified sparks to get out of bed to do the check (it's £10 per breaker, with an extra £10 per appliance in the real world).
In order for any caravan centre/repair merchant to be able to start offering inspections/test on anything 240v related, the person carrying out the test is going to need 2391.
That qualification on it's own is going to cost them £1000's to get the people through, and you can rest assured that if they weren't sparkies before they took the test - they certainly won't be considered sparkies after they pass either.