(23 Jan 2021, 3:58 pm)Storx wrote tbf the distance isn't much different between South Shields and Sunderland Depots. Remember the runs end at Fellgate (X20) and Boldon (30) rather than South Shields and there appears to be some interworking with the E's in the evening aswell.
If they slightly interwork with the E's then that would make sense that they've transferred to sunderland.