I do believe the Kings Cross Cravens cars were actually ordered by the ER for the GC lines rural area, but in a change of plan before delivery, possibly the regional boundaries change of 1958 described above, were taken from there and sent to Kings Cross instead. Being of the "low density" type, just two doors per car, they were completely unsuitable for such suburban work, and the only such on any London terminus work. Possibly being short frame cars the ability to work to Moorgate had something to do with it.The GC lines went to ER on nationalisation but were early victims of the “penetrating lines” split whereby some responsibilities were transferred away. For the GC, in 1950 the WR took over the lines between Marylebone and Northolt Junction and Neasden to Harrow. They retained them until 1958 when the whole of the GC main line went to the LMR.
However, the ER still retained the overall operating responsibility for the route and Neasden shed remained an ER shed (in the KX district) until 1958 when it went to the LMR. Neasden was the original location the LMR considered for DMU maintenance before settling on Marylebone.
I think the line got the best DMU deal with the 115 sets. If it had been a line that was fully WR, 3 car sub sets would have been the order of the day and an interesting thought is if the ER had remained in charge. If the 1950’s KX suburban electrification scheme had taken place, would Marylebone have got their Cravens?!