I can't be sure, I honestly don't remember... I'm only sure about the vehicle but if they're not required to marked, I guess I don't have a case! Thanks everyone for your help

Hello all, I parked on a yellow line yesterday (4th June) and was issued a parking ticket. Although the sign said Monday to Saturday, I was always under the impression that it was OK to park on a yellow line on a bank holiday. This seemed to be the case for plenty of other cars on the same street as well. I've taken a look at the council's website and it turns out that this is a common myth... The only part that seems to be in my favour is that the traffic warden was definitely in an unmarked vehicle and possibly plain clothed (I'm not entirely sure). Do I have a case here or should I just pay the fine? Thanks in advance, Sue