This is one of the 'Diving Beetles', they spend most of their lives in water. Unfortunately someone better than myself with beetles will have to give you an exact ID. They are very nice lookers and can be quite large!
Hope this is helpful
Thank you very much Crystal. I didn't expect an answer so quickly - that's great.
I'm now exploring the rest of the forum - I didn't know it existed until last night!
As Crystal has allready said this is a Great Diving Beetle Dytiscus marginalis and a female going by the ribbed wing covers. Always be very carefull handling these fellows, I know this from personal experience when one bit the side of my finger and left a painful and bloody hole in it.
Thanks a lot for your help.
I'm glad I didn't know about their nasty nip before now - my daughter had it on her hand for about 5 minutes!!
I've also now discovered some amazing pictures of this beetle in action underwater:
What an amazing creature!