Work the dagenham to garston car trains and china clay trains through the tunnel.
Also some unit moves through the tunnel.
They have been known to take the china clay tanks as far as Carlisle, but that hasn't been happening recently.
The GBRf 92s aren’t exactly taxed at the moment. Do they have any other booked work other than the sleepers?
Their fleet of 92s will be a bit more stretched once the Mk.5s come in. Sleeper work will require 7 92s on a normal night (2x ECS in London and Glasgow, 4x for main runs and 1x for Edinburgh - Carstairs).
It's likely they'll also have 2 at the tunnel and another one on the Dagenham - Garston cars mentioned above. That could see 10 in use at any one time, which is the current fleet size.
I'd assume there'll be at least one or two spare for the Sleeper, which could mean all 12 locos (if you include the returning 92006 and 020) have an assigned duty at once.
Also need to bear in mind that there'll sometimes be one or two out of service for routine exam or other work.