They are a bunch of wind up merchants. They knew I was working a few yards away and soon after they started the job the third one came galloping around the side of the workshop brandishing the fire extinguisher yelling "oh no! this isn't going well!" Buggers, they are always teasing me about my car. Anyway, (unbelievably!) said battery was installed and it seems she had no idea she'd been interfered with as there was no dramas with lights or anything. I hadn't realised there had been such a dip in turnover speed as there was with the old battery compared to the new one.
I shall get them back very soon!