The LNER Encyclopedia

This locomotive [a J??, and the only remaining one in its class], was shedded at Malton [50F] until its demise [1950]. It never had a BR number, and so it retained the 'E' prefix until the end.
It was involved in goods duties around the Malton area and it remains as the only steam locomotive in which I have taken a cab ride: whilst it was shunting wagons of limestone at Hovingham [from Wath Quarries], I got chatting to the crew and was given a 'trip' in the station yard! Happy days.

The only LNER number 5656 I can think of would have been an Ex-NER J25. Before the 1946 re-numbering it was nmber 1981 I think. (As seen HERE)

Although many of the class were withdrawn in the 1950s, from what I can tell it can't have been the last of it's class at the time you describe, as they were in use at Tyne Docks up to 1962, and the last one was withdrawn in 1963. It was only allocated to Malton shed in October 1950 and finally returned to York shed in Feburary 1955.

Also, the loco itself did indeed carry a BR number, I doubt it would have carried the E prefix as late as March 1959, when it was re-allocated to Gateshead (52A).