Well my mechanic briefly looked at it as it was slightly pissin down yesterday. He tried spraying WD40 onto the belt but that didn't work (didn't make it squeak either) he said take the belt off, start the engine for a couple of seconds, if it still makes the sound then the engine is fergugered if not take the alternator off, clean it up and spray wd40 on the moving parts (he thinks it could be the baring)