Helio Courier is a rare bird in Europe. Shape and size is about right for Britten-Norman Islander but I'm not sure if I can make out two engines and shape of nose is somewhat unclear too. Anyway tail and wings look about right and RAF and British Army have been using Islanders, so it's a distinct possibility.
I looked at Islander photos at airliners.net and there seems to be two variants of the shape of wingtips. Some seem to correspondent to the threesides view you linked and some look a little more angular, they seem in fact to follow the dotted line shown in that view. http://www.airliners.net/open.file/0995331/M/
It is a very old single seat convetinal glider. It has to be winched up as being pulled by a tug aircraft wood break it rather quickly, Its named the Grasshopper not to sure of make and type, but it is good fun to fly. It can reach a height of 800feet (depends on the weight of the pilot).
http://en.wikipedia.org/wiki/Helio_Courier
Wiki says the Courier wingspan is 39 feet but GE saysthis plane's wingspan is 46 feet. Also 30 feet vs 33 feet long.
http://en.wikipedia.org/wiki/RAF_Northolt
The horizontal stabilizer looks right, but what about the wingtips?
http://www.airliners.net/open.file/0995331/M/
Looks about right.