Peter Green has sent in the photograph of a Vincent which he copied from a Box Brownie-type print and blew up.
The six-bladed propeller mounted in front of the observer's cockpit is not, as might be thought at first glance, a target-towing winch. It is almost certainly a wind-driven pump for the anti-locust spray employed by the Anti-Locust Flight against, we are reasonably certain, locusts. Although the serial cannot be seen, it has 'C' type roundels so is seen after mid-1942.

Самолёты на фотографии: Aircrafts on the photo: Vickers Vincent / Type 266 - ВеликобританияUnited Kingdom - 1932