66621 passes Hungerford Common on 20 July 2021 with the 6M20 10:38 Whatley Quarry to Churchyard Sidings loaded stone hoppers. Although it seemed to be running alright here, there was clearly something wrong, as in addition to being pointlessly looped at Woodborough, it had stood at a red signal for a while near Bedwyn, and was now 21 minutes late. Things would get worse, as after further delays, it passed Reading 91 minutes down, and at one point near Acton was 109 minutes late.