I spent a lot of time on Sunday trying everything that had been suggested. Resetting the box, resetting the router, disconnecting and reconnecting the Ethernet cable (It’s always been hardwired). All I got was the same message that On Demand would be there in a minute.

Gave up, watched TV, went to bed.

This morning it’s working, On Demand apps are there and working, Showcase is working, “Earlier” is available and I get the watch from start logo appearing.

Thanks to everyone who helped, fingers crossed it stays that way.