I had been putting off the snug bay window. The roof falls towards the house and has leaked for a long time. A temporary roof covering went on over a year ago after we knocked off some failed plaster and found wet structural wood behind.
The reason I had put off the job was concern about rot in the lintel visible from below. Thankfully it was nowhere near as bad as I feared. The bearing surface had rotten causing the lintel to fall by about 10mm, but the rot was localised and the rest of the beam was still in surprisingly good condition.
All the beam needed was a new end. A steel plate will now act as a bearer for the lintel. Next job is to fix the hole that has appeared in the bay roof. I’m planning a new bay roof that falls away from the house.