Definitely Pete's option 2, but without the sale of items. Rule 1 will be invoked quite a lot, but nothing will look too drastically out of place.
So for me, I will take Johnster's help and summarise it as follows:
The train will come in and go to the platform, awaiting the fans. This might also include some box vans, plank wagons and luggage vans. I.e. anything where someone can clamber on. A class 47 will then couple up and haul the train away. The loco that pulled the coaches in (likely to be a small tank) will run light engine out, then come back later with more trains. Does anyone know the teams that were in the same league or level as Cardiff? This can help pinpoint which region would be running. Also, would a Hunt come in for a train from the East Coast?
Thanks!