In reply to:
Cockney rhyming slang?
Not necessarily EJ, normally cockney rhyming slang uses two words to describe another...
Apples and Pears = Stairs
Boat race = Face
Plates of Meat= Feet
and so on and so forth
And Im sure zigbot is amazed that this subject cropped up purely coincidently.
I actually think the word derives from old gay slang words, as in NAF ( not available for fun ) as used during war times on board ships, I saw a very good documentary once on the use of old slang words.
Of course over the years NAF has come to mean other things, namely old or dated etc...
So the use of the word troll was used as in looking for trade / sex.
And NO I have never trolled anywhere
London Bye Ta-Ta...