I spent a couple of Summers working on the lock, and took this photograph, probably with my mother's old Kodak box camera, in September 1961.

The lock is being emptied to allow Maid Marcella to proceed downstream towards Abingdon, an the water level is at about the half way mark, so you can see that the drop is is really quite alarming!
The lock keeper at the time was Mr Ron Older, and he is the figure at the extreme left tending the lock garden.  Most lock keepers were keen gardeners, and competed in an annual competition, I seem to remember.  They may well do so still.

The lock looks very different today, it was long since entirely rebuilt, and equipped with electro/hydraulic mechanisms to operate the paddles and gates - it was all manual labour in 1961.