Many of you will know better than me, but I’ve guessed that this is a DC3 preparing for the D Day anniversary flying over Hampstead Heath
I saw a formation of four of them late this afternoon. Heading in the direction of Duxford, probably after beating-up Cambridge airport (common practice for aircraft judged interesting). Too far away for photos given the time needed to get my camera out of the bag on the bike's rack. Binoculars already hung from my neck confirmed identification.