Hi Mike
The trip was on Saturday – we were showing some visitors around London so wanted to use the river boat.
Turns out the day was £14.50 in all, using contactless. The river boat from Millbank to Greenwich was £8.70 of that!
I was hoping there might have been a cheaper way to do this (there were 5 of us – one adult with a veterns card which covered all except the river boat), but seems there may not have been!