10th December 2019 · 125 Group – Preserving an HST

Presenter: John Zabernik of the 125 Group

Recent events brought a significance to the topic on 10th December when John Zabernik of the 125 Group presented “Preserving a HST”. He described the background to the development of the prototype HST and the detail of the layout of the power car which allowed removal of individual large components for repair or replacement. The braking system was designed to stop from 125 mph in the distance that 100mph locomotive hauled trains stopped to avoid replacement to the spacing of existing signals. During testing the prototype achieved a new world record for diesel trains.

New Mark 3 coaches were developed taking the best features from the earlier Marks 1 and 2 plus many improvements including being 3 metres longer.

A redesigned cab and nose shape were required for the production version which took up main line duties from 1976 significantly reducing journey times. The world speed record was broken again and during over 40 years front line service the Valenta engines were replaced by more efficient units. By the end of 2019 they will be withdrawn from GWR and LNER main line service with EMR and Cross Country continuing until new replacements arrive. Modified shorter sets are now in use in Scotland and the West.

The prototype was stood down from service in 1976 but retained for departmental use then one power car displayed at the NRM.

The 125 Group was formed in 1994 with the aim of preserving a HST set. A number of Mark 3 coaches have been obtained and restored. They arranged an agreement with the NRM to restore the power car to working order with a Valenta engine to run with their restored coaches. The work was carried out at Neville Hill depot with significant help and parts donations and then transferred to the GCR (Nottingham) where work continued and line trials undertaken before public service commenced in 2015. The set was taken to a number of heritage railways but then after engine problems the power car was recalled by the NRM in 2019 and is now at Locomotion Shildon. The Group have been promised production units 43048 and 43089 when their use by EMR has ended to complete their aim of a preserved working set.