Reminds of anomoly which I think got to court "Up North" (Calder Valley?) where a service was advertised as second class only, presumably 14Xs, but quite often 15Xs would turn up with first class so everyone piled into First. Not sure if it was end of BR▸ or first of TOCS, but whoever tried to excess the and it got to court. I think the court found in favour of the operator.
Are you sure that is right. It was my understanding that if the service was advertised as SC only, then regardless of the stock that turns up, there is no
FC‡ and SC ticket holders can sit anywhere.