It was a RAF-Avia steed if that helps ? There are those DC-6's that are based/land there, so it's not out of the ball park.
YL-RAD has been active over the UK for the last couple of days, so that's probably your bird. If it went into North Weald it would be the largest aircraft to have landed there for quite a while, but nothing's impossible I suppose.
The "based DC-6s" there are actually a C-54 and DC-4 pair, and are only "based" in the sense that they have been sadly rotting away there for the last 12 years and seem unlikely ever to fly again.