Hi,
After a cycle survey, there is no evidence for anything other than a private garden here.
The nearby alley has a wooden fence, and you can see a domestic greenhouse and grass though the pailings.
Allotments in this area typically have external signage from NCC, and cover SIGNIFICANTLY larger areas.

Based on my survey of ground truth, I have removed the landuse=allotment, and aligned the outline with the geometry offset in use throughout this area.

Survey GPX:
https://www.openstreetmap.org/user/James%20Derrick/traces/3633289
Changeset: 102746900
Happy Mapping,

James