This was the final delivery of this series of drop-side wagons and were supplied in 1925 with the arrival from the Metropolitan Carriage & Wagon Co., Ltd. of Saltley Works, Birmingham - but were not permitted to be used until paid for the following year; they were stored at St. John's Station until this time (some records indicate their build date as 1926 for this reason).  Of all the seventy eight wagons of the series supplied these were the longest lived and three survived past nationalisation.  M.71 (together with M.61 and M.66) had their wagon side removed in 1967 and tanks fitted for the short lived oil trains.  Of these twelve wagons, some of which were the longest surviving and represent the sole surviving member of the series, M.78 was restored by the Association in 1998.  M.71 (together with M.61 and M.66 of a previous batch) had its sides and ends removed and was fitted with tanks from road tankers for the short-lived oil train traffic.  *M.70 was stored latterly at Santon Station, and was dismantled to provide parts for M.78.