That's a cracker of a shot Saint-Ex! Looks like an early morning departure from runway 28. A shame that the registration is not legible but is a very atmospheric shot. A few years back I had the opportunity to wander around Wisley with Maurice Ungless, who used to work there in the early 1960s and I have some of the photos from that day on this page:
https://www.vc10.net/Photos/Wisley.html Any chance I could add your photo to that page?
On the topic of photos, I received the photos that
ex82watcher found just a few days ago, thanks! Most of them are detail shots of aerial installations or avionics boxes as his neighbour used to work in the avionics department at BOAC/BA. There are sets of flight deck photos as well that show the early configurations of the BOAC flight deck and the RAF C1 flight deck, I will see if I can add these to my site on a separate page in the near future. I did just add two photos to the page about XR806, see here:
https://www.vc10.net/Airframes/cn_826__XR806.html (second row, first two images). These are the only two photos in the set that show a bit more of the exterior, and one of them happens to show the trial installation of the inflight refuelling probe on XR806. This was done at Wisley in the mid-1960s, before XR806 was delivered to 10 Squadron and it would take another 20 years (almost) before these probes would become a common feature on the C1 fleet.
As for the registrations of the BOAC Supers, they were allocated in sequence so any abbreviations, like the one you suggested
25F, are purely accidental, however fitting they may be.