In the 1950s, there were attempts to improve the service on the branch line. Over time, permission was given to electrify the line in 1957. However, because the electrification did not cost much, the branch was only able to have special two- or three-car trains running on it. This was because the power supply was not strong enough to support trains that had more cars. Another problem was that the stations on the line had short platforms. This would mean that the normal 8-car trains would not be able to stop at them. Because of this, the Epping-Ongar branch line was normally operated separately from the rest of the Central Line. However, for two days each year, trains did run through from London. These trains would terminate at North Weald for the airshow on the Saturday and Sunday of its opening. The normal Epping-Ongar service would get around this extra service by passing the train on the other line at North Weald station whilst it headed towards Epping. The train from London was run as an extra train on the normal Central Line timetable. However, this extra train was only four carriages long instead of the normal eight.