Running 55:00 
I was pleasantly surprised that the back was better this morning and running was possible. Still doing 7 repetitions of 5 min running and 2 min walking.
Trip to the physio was ok so I'm going to increase to 8 repetitions this week. The goal is to get up to 11 (which is roughly 1h15m) and then I'm not sure what we do next to build up.