What markings did it have?
Probably a C-47 flying in from the USA.
A whole stack of them (30+) are gathering to go over to France on 5th June for the D-Day anniversary.
Was it one of these?
https://www.daksovernormandy.com/aircraft/
More details here -
https://www.military-airshows.co.uk/press19/daks-over-normandy-duxford.htm