The rules were formerly that Cadets over 18 and adult staff could do the courses, back in december they changed the rules so that only adult staff could do the courses, I forgot about that little detail.
Halton's about 70 miles from Lancaster to whoever it was that was asking (according to google maps anyway). I've had to massively postpone doing the course now anyway as you can't do the course as a cadet now after the Cadet Centre for Adventurous Training decided to make it so that only adults can do National Governing Body courses. It's not like they now can't get enough people to make it worthwhile running the course when I know that at least one of my friends (and myself) would have gone on the course making it worth while running the course...
Martin, I was only able to find two pairs of trousers like that before I bought mine back in December, the Paramo Torres and the Softie trousers which I linked above. A member of staff at CCF bought a pair of the Torres trousers and I bought the softie trousers, they are almost identical except that mine have a green and a yellow side (they're reversible so that troops can use them over here or in the sandy places). Both are incredibly easy to get off, you don't even have to lift your feet off the ground to get them off. Also, how's a maximum of £20 delivered expensive for something you may not use much?
Just stick 'em on top of your trousers, when you get too warm pull the zips down and throw them into your bag. That said, they have a HUUUUGE waist, I had to get a medium and I'm a 34" waist, there's also no belt loops and they can drift down. So you may have to stitch a couple on yourself.
Oh yeah, don't order from the website I linked to, I'd suggest trying fleebay for a pair.