HH – you might be right there mate, though idiots attached to groups who do that sort of thing would probably find it quite easy to get their hands on some sort of explosives.
A life like resomblance might be easy to find on the Internet, but you must have some conviction to put the thing together, take it to the match, smuggle it in and then go through with it.
Hopefully cctv will show who did this and they will be caught quickly.