From Bill Read: On Sunday 16th July 1961 Class 105 power-twin (leading) + 2 x Class 113 units (cars not identified) struck the rear of a stationary ballast train which had been carrying out track work. 7 persons killed and 116 injured. The first three cars were severely damaged. Slack operating practices and misunderstandings allowed the DMU (on a Colne – Fleetwood express) to be given clear signals into the occupied section. Although the cars were not identified, Class 105 power-twins M50783 and M50808 were `missing` from the 1962 ABC. It is possible that they were the ones involved, as they were all based locally and I know of no other serious accident which involved this type of unit at that time.
From Andrew Dyson: The train involved was a special excursion. It was advertised along with others, in a very big advert in The Accrington Observer & Times on 08/07/61. The fare was 5/6, it left Accrington at 11am and Church and Oswaltwistle at 11.04am. Return time from Fleetwood should have been 8.06pm. The Class 113's involved were 51780 and 51755. My dad remembers this as the set had been on display at an exhibition, possibly Derby, and returned to Accrington in immaculate condition.
According to Ashley Butlin's DMU Disposal: British Multiple Units Vol 1, DMU's and DEMU's, 51780 was cut up at Derby c&w in 9.62. This is also the date given for 50783 and 50808, so I would assume that these were all involved. As 51755 survived, it must have been the back unit, with the 105's leading. I know one of the units overturned. There is also a photograph that I have seen published showing survivors of the accident just after it happened. Unfortunately the micro film for The Accrington Observer & Times dated 18/07/61 which covered the crash, is missing.