Go to St Saviour's and take the path on the left of the entrance,
F.A. Bevan, I think, is Francis Augusts Bevan (1840-1919) who was Barclay's Bank's first chairman. The Bevans were Quakers, but I can't find a Quaker connection for St. Saviour's.
A.J. Ard was interviewed by Booth and a Rev. A.J. Ard sailed from Liverpool to Quebec in 1904.
That's all I can find about them.
Anyway, the point is that this is an illogical, inefficient, uneconomic use of space. There's an old joke about an economist seeing a £10 note on the pavement and not picking it up because if it had been worth anything someone would have done it already. This is the land use version of that, space that somehow escaped becoming something useful and so stays there, a patch of miraculous scrubland in the middle of London.
It'd make perfect allotments.