Silly question, but how long do crews need for their rest period?, I always thought it was 12 hours from sign off to sign on but that wouldn't work very well, especially on the Fort William run.
I believe that the minimum rest period between shifts for sleeper hosts and team leaders (I.e. the non-safety-critical sleeper staff) is 9 hours. This makes it very tight for the one London-based host coming back from Fort William southbound on Monday, Wednesday and Friday nights if the inbound working is late. However, the Fort William portion should, if fully staffed, have a Fort William based team leader and a Fort William based host looking after coaches D and E (with the London host looking after F and G on a Friday morning northbound and southbound). If the northbound is late on a Monday, Wednesday or Friday morning, and is already seriously late at Edinburgh, it has been known for the London host to leave at either Edinburgh or Glasgow Queen Street, with the London host lodging in either Edinburgh or Glasgow and leaving the two Fort William crew to carry on alone back to base. Then the southbound will be worked by a fresh Fort William crew as far as Edinburgh, with the London host meeting the train there after midnight. This happened on a Monday of severe delays at the end of April, and this usually solves the problem of crew hours.
However, if there are not enough fresh hosts at Fort William to work the southbound, there will still be problems. Also, when the southbound was last cancelled due to crew rest hours after the air leak near Tulloch in June, it was the case that the London host had no opportunity to leave the train and had to stay on until arrival in Fort William at just before 14:00, leaving him in no fit state to work the southbound train at all. There also may not have been enough fresh crew at Fort William, hence there was no option but cancellation.
I would probably be more worried about the Aberdeen portion southbound tonight, as this has to be worked by two London hosts and a London team leader, who will need a full nine hours’ rest before booking on again. It will either leave very late or be cancelled, unless a contingency crew can be found (and CS do not have many spare hosts and team leaders at this point in time).