Of The Bull and Cow and Such a Row

I was in London last week and ended up having a pointless row with a taxi driver over a fare.
The issue was that I owed him £8 and I gave him a tenner (or a Paul McKenna as the Cockneys might say). No ordinary tenner that is for I gave him an pristine Ulster Bank ten pound note. The look of disquiet on his face told me that this transaction wasn't going to be easy. "Is that all you have? Don't you have any proper notes?" I explained I didn't but that he shouldn't worry because being sterling and Bank of Ulster it was legal tender it. "Listen my friend that's not legal tender here and I'm not obliged to take it". I politely replied that it was and he was. He promptly explained that it was in his rule book that he wasn't obliged to take it and I shouldn't try to tell him his job". Impolitely, I asked him to produce this great fount of all knowledge which he failed to do although he did threaten to produce the police (no doubt by getting on the "dog n bone").
After alighting I googled furiously to find out who was right but my research was inconclusive. Can anyone help me solve this mystery I wonder? Who was right? The cabbie or the customer?