In the morning we worked singly through Beeston Iron Lock as suggested by BW. Apparently although it looks a wide lock its not wide enough due to the warped iron plates and the danger of snagging on the sides of the lock. Ben's walk was delayed til later as the towpath had been invaded by a motorised grass mower! Ben could get away fast enough- he wanted to get back on the boat.
There was an excellent view of Beeston Castle from Wharton's Lock although the photograph doesn't really show the height of the outcrop compared to the lower level of the ground around. Ben and I walked for a while in the pleasant countryside with the boat travelling slowly alongside. Ben loves running free along the towpath and when nobody else is about it's even better.