Spiky, get a loooong breaker bar, rest it on the driver's side wing while the socket's in, put the car in reverse and turn her over... that'll get the nut off

Nah, seriously, lump hammer on breaker bar did it for me, pulled the pulley with a jobbie (harmonic balance puller) I got from local motorfactors, has three bolts that attach to the pulley. Soak it in WD40 the night before, came off like a dream - but that's not always the case apparently...