1S96 16:18 Willesden-Shieldmuir as confirmed by
Falcon1200, which failed on the down line before Lockerbie and so the Highland sleeper eventually passed it on the up line once single line working was implemented.
1S26, the Lowland sleeper, was held for an hour in Carlisle before heading to Lockerbie and being held for another 30 minutes whilst 1S96 was moved out of the way, so 1S26 didn't use single line working over the up line (by that time it was probably starting to get too busy with up trains)