As @Creaky quoted me later, we had paper booklets you used have to show to driver, though I think people just pilled on from memory.
Though as you say, it would be pretty pointless any none football going fans getting on as it its chaos and the bus is not stopping until you get the AMEX.
I'm pretty sure during the first couple seasons at the AMEX you had to show your season ticket to get on the P&R at the Race Course...... or maybe I'm imagining that ???