As per an alert from Wikipedia, this sense does seem unlikely. --Connel MacKenzie 23:32, 24 May 2007 (UTC)
It is the normal use of the word in the UK. Here is the OED . . .
Brit. Criminals' slang. - A sexual deviant; a person convicted of a sexual offence, esp. child abuse. SemperBlotto 07:32, 25 May 2007 (UTC)
A nonce is a child molester or someone who is a total twat. I think this underlines how different American and British English can be and how unaware we are sometimes of each others idiosyncracies when it comes to language. For my pals across the pond, if you watch a few films such as Lock Stock and two Smoking Barrels, Layer Cake etc. the term is probably used their, you may have to listen carefully for those cheeky southern chappies!--Williamsayers79 08:22, 25 May 2007 (UTC)
I can confirm as a UK resident that this is a well-know, widely-used meaning for 'nonce' here, and as SemperBlotto mentions, it's also covered in the OED. See http://www.londonslang.com/db/film_slang/ for usage in Lock Stock and two Smoking Barrels. That said, I'd question the "paedophile" reference; although many people do use "paedophile" synonymously with "child-molester", strictly speaking, not all paedophiles commit sex crimes, as was pointed out earlier within Wikipedia. Tws45 13:58, 25 May 2007 (UTC)
I'm taking the RfV off as I believe it has passed. --Williamsayers79 18:17, 6 June 2007 (UTC)
Meaning : The slang definition of paedophile is not very good. The word is in wide circulation here in the UK and its general meaning is Police informer. (or 'grass') I think the other meaning comes from that because police informers and paedophiles are equally loved groups in many communities here. Not communities I am part of BTW. - Lucien86 19:53, 30 August 2011 (UTC)