Bogie 40 ton hopper wagons were first introduced by the LSWR in 1903/4, for the movement of Ballast from Okehampton (where the company owned the Meldon quarry) to all corners of their network. Upon grouping in 1923, the fleet needed both replacement and expansion for the much larger area Meldon quarry then served, leading the SR to build numerous wagons derived from the LSWR design. This started with the diagram 1772 wagons in 1928, which were followed by the dia 1774 wagons in 1935 and lastly the dia 1775 wagons in 1947. The three SR types were all similar with minor variations, for example brake equipment and hopper angles but the largest visible change was the move to AAR-pattern cast bogies for dia 1775. The SR types were later supplemented after nationalization by BR dia 1/585 built in 1954, a near-identical wagon to the dia 1775 apart from the use of GWR-style plate bogies, which were largely inadequate for the task required and frequently suffered broken bolster coils and worse in traffic. Also closely related were the longer 50 ton capacity BR WHALE wagons, which again had poor plate bogies.
In BR ownership the SR and BR wagons were all given the Fishkind ‘WALRUS’, with wagons remaining upon the introduction of TOPS getting the code YGV. The SR-built wagons had a long service life and lasted into the 1970s, with many being transferred from the Southern Region and ending up as far away as Ladybank, Scotland. The wagons were eventually replaced in BR service by the SEALION type wagons, a further development of the SR design with dual braking and more modern Gloucester bogies, and the SEACOW, and air-braked variant. Construction of SEACOW wagons ended in 1982, with over 700 SEALION and SEACOW wagons constructed. Due to their unglamorous nature of work, the wagons were rarely photographed in service, thankfully a handful have lasted into preservation which is a testament to both the soundness of the design & their usefulness.