Well, an example, I was cover (the booked turn) on Sat and I worked 2 hove shuttles and then went to Ore and back (from Brighton). The Ore and back was covering an Eastbourne duty.
If you do get overtime, they can only pay you up to max of 12 hours. Sometimes if you end up being at work for more than 12, they will give you the extra another day, but even sometimes that does not work.
eg: one cold night I was working a late turn which involves the 01.00 Vic to Brighton. That night due to engineering work, it was due to run to three bridges where a bus would take the passengers and a taxi me and the driver. Due to network rail issues, we got stuck at Redhill. I arranged for the buses waiting at Three Bridges to come up to Redhill to take the passengers on to Gatwick and Brighton, we were then asked to run the train back to Victoria. When we got there, there was not enough hours left on the drivers shift to work it back down, so we took a taxi back to Brighton. He then got lost. I got back to Brighton at 05.50. (13 hours at work) Since i was due to start at 16.50 later that day, I was unable to start work unitl 17.50. I then got caught in other delays, which meant i worked 11 hours that night, so I was given more overtime, which was added to the next day etc etc.