DBSO 9703 and 37610 operates the monthly PLPR test train 1Q97 Welwyn G.C. F.D. to Clacton-on-Sea but when it reached Thorpe-le-Soken it strangely changed head code to 2Q97 to go on the Walton on the Naze branch line then it returned back to Thorpe-le-Soken and changed back to 1Q97 where it continued it’s journey to Clacton-On-Sea
