Try to find the spot where the photographer was standing.
Google Streetview
[https://www.flickr.com/photos/gnmcauley] Hello! That Ford Zephyr Mark IV (centre frame) did not happen until 1966 according to en.wikipedia.org/wiki/Ford_Zephyr#Zephyr_Mark_IV
The oncoming car is AIA 9841, which would have been registered maybe June 1967, the Zephyr has a BIA reg, so later still. It might be 4117, suggesting half way (say 8 months) into the BIAs, so registered early in 1968.
Niall McAuley
Google Streetview
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[https://www.flickr.com/photos/gnmcauley] Hello! That Ford Zephyr Mark IV (centre frame) did not happen until 1966 according to en.wikipedia.org/wiki/Ford_Zephyr#Zephyr_Mark_IV
Niall McAuley
The oncoming car is AIA 9841, which would have been registered maybe June 1967, the Zephyr has a BIA reg, so later still. It might be 4117, suggesting half way (say 8 months) into the BIAs, so registered early in 1968.