As recently restored 353 had not previously run in its current form (using a modified PMV underframe), it was necessary to bed in the suspension and brakes; and to build confidence in the performance and dynamic behaviour of the vehicle. The tests were undertaken on the Great Central Railway over a three day period, with mileage accumulation carried out on day 1 (Monday 19th November). For the initial test runs the carriage was sandwiched between two locomotives (Cl45 D123 and Cl20 D8098 ) to enable rapid reversals at the possession limits and build up mileage as quickly as possible.
Once safe operation at 25 mph had been demonstrated on the first day, the carriage was tested to 40 mph, then to a maximum higher speed of 50mph on day 2 (Tuesday 20th November). The Class 20 locomotive provided the motive power for the high speed test, and with the light load of the carriage was very quick in reaching the desired speed. Day 3 (Wednesday 21st November) was booked as spare in case there were any issues earlier in the week. In the event this was used for additional mileage accumulation.
The following amateur footage shows the test train leaving the outskirts of Loughborough during one of the high speed runs.
The GCR was chosen as it has relatively straight and even track; ideal conditions for undertaking brake calculations and measuring vertical and lateral accelerations. The railway had been granted a derogation from the Office of Rail Regulation for undertaking the high speed test. The Institute of Railway Research carried out the safety assurance work for the carriage and conducted the instrumentation and testing of the vehicle with support from London Underground and Festiniog Railway representatives.