To update, the following Ely to Norwich ran to time, so a 1 hour delay if I had just waited at Ely rather than faff about with the bus.
The bus hadn't reached Attleborough by the time my taxi from Thetford dropped me off (recognise some of the cars in the car park and their owners on the bus).
I guess the honest thing to do is claim for 1 hour?
I can't work out why they provided a bus. Passengers would have been delayed less and GA would have saved on the cost of the bus and a tier of delay repay if they'd just told us to wait an hour at Ely.
Odd decision.
Some clearly frazzled station staff at Ely too, heard one being quite rude to passengers and then slagging them off to his colleague in the office, but within earshot of me and several others.