[1] The 12-mile Belfast-Bangor railway line had a well used passenger service and, being devoid of goods traffic, was chosen as the testing ground for the diesel railcar era.

This was considered such a success that the UTA constructed its own experimental three-coach diesel railcar set at its Duncrue Street works, this being outshopped in late Spring 1951, ready for testing and driver training.

To continue its plans for dieselisation the UTA, over the following two years, built another 14 three-car trains in three batches, and by the following Spring (1954) it was able to operate all its Bangor line services with railcars.

In a works visit in mid-1962, intermediate cars 526 and 527 were fitted so that they could run with either Multi-engined (MED) or Multi-purpose (MPD) railcar trains and were not just restricted to their own type.

Under the UTA, from 1951, a Brunswick Green livery was applied to passenger carrying stock and the MED's were outshopped as new in this colour, which lasted until the early 1960s.