I clicked on "Reply" and was informed that someone else had posted, so here is just a little supplementary information.  The search map from Historic England marks the site with the legend "Hospital (site of)".  More interestingly though, the garden wall you showed is listed grade II: " Part of the Mediaeval flint wall of St Lawrence's Priory. 6 ft high built of flint and reused masonry. Brick coping. Pointed arch with stone keystones to No 136". https://historicengland.org.uk/listing/the-list/list-entry/1260530?section=official-list-entry.

Thanks for the good wishes, I should be good for at least a year yet, and if I'm really lucky I might make my three score years and ten in 3 years time.  Just at the moment though the treatment each 4 weeks gives me extreme tiredness for a few days amongst other symptoms, so please excuse me being late to respond on occasion.

The image is taken on the Old Dover Road, Canterbury, and would appear to be the access to a substantial old “black and white “ building, on the corner of St Lawrence Forstal. Another entrance is blocked on the corner of the two roads.

JohnFilmer, I didn't find it offensive as I guessed you meant the management of the NHS rather than the amazing guys at the coalface who have looked after MartinR so well.

Anyway -back to the GTP.

0.5 Km from a hospital
On one of the original routes to Dover.
Railway line 0.5 Km to the left of the photo

Sorry guys, my post was meant to be humourous not offensive.

Back at the plot, any further hints? Not got anywhere with it for the last hour.

I know it's fashionable to dish the NHS and I'm also very well aware that waiting times are far too long, however, the NHS generally and specifically both Maidstone Maritime and the Kent Oncology unit have kept me alive now for 5 years after diagnosis with aggressive metastatic prostrate cancer (oh and also dealt with a bladder tumour on the way).  There most certainly are modern functioning hospitals.