Yes that is right. There aren't enough 317s to cover everything and the 379s were only allowed to run solo until Wednesday. Two pairs of 379s turned out on Thursday but the Stansted pair failed early afternoon and was replaced by 317665 on its own. This worked 1610 from LST which was full and standing from Tottenham Hale. Today 317340+337+664 ran as a 12 car on one of the triple 379 rush hour jobs. I've not seen or heard of a 12 car 317 on that route before.I assume that the 379s not being able to work in multiple is the cause of the short forming on West Anglia that have appeared since?