Strange goings on at Didcot North Junction on 31 July 1992. It was commonplace to replace a defective driving car from one of the Western Region Class 117 three car units with a Class 121 'Bubble Car', and indeed that's what I thought this was as I took the picture. However, this is in fact half of a Chiltern Line four car Class 115 set (led by 51677), working in multiple with 55024 (L124). The 115 (complete with Chiltern Line branding) is well off its normal route here as it works the 2C64 16:43 Didcot to Oxford 'all stations' Network SouthEast service.