For the attention of 2 stroke ted,the word your'e is like you say an abbreviated version of the words 'you are' but that is not the word he should have used at all ,like you have suggested.It would have then read with the same meaning as this.
Paul, I think you are girlfriends moped is the least of her worries.
unlike this which he wrote which does in fact make complete sense and is gramatically correct.
Paul, I think your girlfriends moped is the least of her worries.
so to sum it up victor meldrews dad is in fact apologising for no reason and his son victor meldrew was in fact correct all along with this sentence.
i would stick to 2 strokes and not teaching english.
regards,
albert einstein
p.s rock on victor you're right.
Albert einstein, February 2010