As part of the deal that allowed the Company's trolleybuses to run into the centre of Rotherham, Rotherham Corporation vehicles ran out to Kilnhurst, to Conisbrough Low, and to the Adwick Road terminus. Mexborough & Swinton used letters to identify their services, while Rotherham used numbers, apart from their un-numbered service to Templeborough. In some cases, both companies ran vehicles over the same route, which were identified differently depending on who owned the particular vehicle. Thus Mexborough vehicles running between Conisbrough Low and Rotherham were running service "B", while Rotherham vehicles plying the same route were running service "9". The fleet was augmented in 1937, when six second-hand vehicles manufactured by English Electric were purchased from the Notts and Derby Traction Co, and again in 1942 when six 3-axle vehicles made by Guy Motors arrived from Hastings, although not all of this last batch entered service. During the Second World War, the Company bought six utility-bodied Sunbeams in 1943, and after hostilities had ended, bought 33 more Sunbeams in three batches, allowing all of the pre-war fleet to be withdrawn.