37421 passes Uffington on 6 October 2022 with the 1Z23 06:41 Bristol Kingsland Road to Derby RTC Network Rail test train, with 37116 bringing up the rear. The previous day's 1Z22 07:13 Derby RTC to Bristol Kingsland Road had been retimed as the 1Z22 09:10 Coventry to Castle Bromwich Junction and 1Z22 08:39 Castle Bromwich Junction to Bristol Kingsland Road, and had missed out the Cotswold Line, which was effectively closed due to the ASLEF strike. As there were still no passenger trains over the Cotswold Line on this day, it was a little surprising that 1Z23 went back via the line (running over an hour early), therefore becoming the only train to traverse the Cotswold Line on 6 October!