In the 1950s British Railways was investing in a new generation of diesel multiple-unit to replace steam; the new units were cleaner, more efficient and attracted back passengers to the railways at a time when the economics of the industry were deteriorating markedly. This was the era before the Beeching Report, when the country still possessed a sizeable network of branch and secondary routes and when these were still perceived as having some for of future. The results from the early experimental use of the new DMUs were encouraging from the initial Derby Lightweight units and, as a result, BR commissioned the construction of a vast number of DMUs, from a variety of manufacturers, in the late 1950s.
Although construction of the Derby Lightweight units had effectively finished in 1956, in late 1957 it was announced that an experimental two-car unit was to be constructed that would be powered by batteries. The new unit was designed to operate over the line from Aberdeen to Ballater. It was planned that the unit would be largely charged overnight with to-up recharging during the layover at either destination. According to The Railway Magazine report of the time ‘If the results are successful, there may well be a future for these railcars in areas where traffic is light.’
The two cars were constructed at Derby. No Sc79998 was a Driving Motor Brake Second and was completed in March 1958 to Diagram 406 and Lot No 30368. No Sc79999, a Driving Trailer Composite, was also completed in March 1958 to Diagram 442 and Lot No 30369. The former had 52 second class seats, whilst the latter had 12 first and 53 second class seats. The new unit was powered by two 100kW Siemens-Schuckert nose-suspended electric motors which were supplied by 216 lead-acid cell batteries. The two-car unit weighed almost 70 tons, with the batteries weighing 17 tons. The two-car set had aluminium bodywork; this was to prove invaluable when the vehicles were ultimately preserved, as the condition of the bodywork after nearly 20 years in departmental use was excellent.
Based in Aberdeen, the unit entered service on the Ballater branch, where they shared the duties with a conventional DMU. In the winter timetable of 1962/63, there were six return workings a day between Aberdeen and Ballater and the BEMU was allocated to the 8.9am, 1.55pm and 6.10pm departures from Aberdeen and the 10.3am, 3.25pm and 8.3pm departures from Ballater. The journey times to and from Aberdeen were between 80 and 90 minutes for the 43½-mile long route.
The original batteries were replaced in the early 1960s but the new batteries caused a number of minor fires that resulted in the unit’s temporary withdrawal. The Ballater branch closed on 28 February 1966, a casualty of the Beeching Report, although the BEMU was no longer in operation at this date. Following the closure of the branch, the BEMU was withdrawn and, after a period of storage at Inverurie Works and then Glasgow’s Hyndland depot, found a new use with the Railway Technical Centre at Derby. Nos 79998/99 were renumbered 975003/04 respectively in the departmental series. The two-car set was used as test train Gemini (Lab 16) until withdrawal in 1984.
Despite the unique nature of the train, preservation seemed unlikely as a result of the significant presence of asbestos. However, fate was to intervene in the guise of the West Yorkshire Transport Museum project; funded by West Yorkshire Metropolitan County Council, this scheme envisaged the construction of a major museum at Low Moor, near Bradford, and the preservation of the Spen Valley line from there towards Cleckheaton and Wakefield. Acquired by the project, a five-figure sum was expended in getting the asbestos removed. Following this the unit was stored briefly in the now-closed BR depot at Hammerton Street in Bradford along with other railed vehicles destined for the museum. Ironically Hammerton Street had been one of the pioneering depots to receive Derby Lightweight DMUs when they were first introduced to public service in 1954.
Unfortunately, however, events overtook the museum; the abolition of West Yorkshire MCC in April 1986 along with the unwillingness of Bradford and Kirklees councils to take over the whole project, meant that the resulting scheme, which opened as the ill-fated Transperience, was much scaled back and had no need for the BEMU.
The BEMU was placed on loan to the East Lancashire Railway, where it was restored and used on services for a brief period before spending a considerable period in store. In terms of restoration, the body was in good condition and much of the original interiors had survived.
Following the liquidation of Transperience, the BEMU was acquired by the Royal Deeside Railway in Scotland and transferred back to its spiritual home between Aberdeen and is now based at Milton of Craithes. At present, the unit lacks batteries — although there are long-term plans to obtain thee — and is used by the railway as loco-hauled coaching stock.
The IPEMU — No 379103 — is a conversion from an existing Class 379 EMU and is scheduled to operate over a five-year period on the Harwich-Manningtree line operated by Abellio Greater Anglia. Whilst retaining its 25kV capabilities for operation over conventional electrified lines, the modified unit is also fitted with batteries. Following the testing of two types of battery, it is now fitted with lithium magnesium phosphate battery technology supplied by the Texan company Valence. The unit was converted by Bombardier at its Derby works.
The rationale behind the construction of the IPEMU is that, whilst the process of electrifying main lines is advancing, there will be a number of secondary and branch lines where the case for electrification cannot easily be made. These lines can, if the experiment proves successful, be operated by IPEMUs. These units would be able to operate conventionally over the actual 25kV network but switch to battery operation on the non-electrified routes.
Operation of the IPEMU commenced in early 2015 almost exactly 50 years after the earlier experiment in the use of battery traction came to an end.