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Derby Lightweight (Yellow Diamond) 1, 2 & 4-car DMUs

Non-Passenger Use

M79649 was a DTC that was converted to an inspection saloon for the LMR soon after being built. By June 1967 it was at Shields electric traction depot, no doubt for use in conjunction with the South Clyde electrification, and renumbered DB999510.

Two other DTCs, 79250/2 became 975013/4 after withdrawal on the Scottish Region in 1967 and seemed to just have been used as staff messrooms/stores vehicles at Craigentinny depot.

799000 at York

One of the single cars, 79900, went into departmental use in 1967 as a Eastern Region route learner based at York. It would be renumbered as 975010. The image shows it in York roundhouse on 9/8/70. David Mant.

By 1974 it had been transferred to the Derby RTC, and gained the name "Test Car Iris". For many years it carried the RTC red/blue livery, and performed a variety of tasks around the country. by 1995 it was repainted into a version of original green livery with small yellow panel.

A 2-car West Cumberland set 79018/79612 went into departmental use as the Ultrasonic test train, numbered 975007/975008.

The image shows the pair at Reading on 25/7/88 Hamish Stevenson.

Eric Stuart recalls one experience about the Ultrasonic Test Train - "I was a driver on the Met at that time and had gone to Moor Park to relieve a driver on an Amersham train. Whilst waiting, the DMU came through at about 15mph, followed shortly by the train I was to pick up. The driver got off and I set off toward Amersham. We stopped at every signal for 5 minutes or so, as the dmu continued its funereal journey. We eventually got to Amersham over half-an-hour late.

Almost immediately, the following 115 to Aylesbury arrived. At that time, the service was hourly and the 'box at Gt Missenden was switched out except in peak-hours. As far as I know, the 115 had to wait over half-an-hour for the test unit to clear the section to Aylesbury or probably to the IB signals somewhere near Wendover.

When I got back to Ricky depot, the SM had been talking to the Controller. It seems the test unit was supposed to have travelled at normal speed to Amersham and then do its test run (15mph or whatever) to Aylesbury. Some wires had been crossed, with lack of amusement all 'round."

When the Derby Lightweights were withdrawn from passenger use in the late 1960s there was no interest in DMU preservation. Thankfully, the Ultrasonic set and Iris survived long enough in departmental use for this attitude to change so they can be appreciated today.

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