I was travelling eastbound on the M4 last night when a large white airliner type aircraft flew over in the distance at Junction 15. From this distance in looked like it could have been a 757/A321/DC8 as it had a long white fuselage.

As I got further along the motorway I saw it banking hard left as if to fly back over Swindon. From this angle it looked as if it were a 727 or VC10. Does anyine have any info on this?

It may be a VC10 that was practicing air-to-air refuelling with the Hercules fleet, but it is very unusual to see a non-military aircraft flying low over Wiltshire.