Nipping out the back at Watford Gap, yes did that do, back in 2001.
At Rugby depot, we did the lunch time 455 Northampton to London Vic, returning at 1500 back to Northampton, then dead to Watford Gap services, which involved going out the back of Northbound over the bridge in into South. There it was grabbing a spot of food, some drivers did actually use their card both sides. as we had well over a hours break there (I never did this and they did get caught doing it), before heading back to London for the night with the 561.
As for now, well I know when I did National Express out of Northampton, doing the bottom end of the Yorkshire Traction services, most of the night drivers used to use Watford Gap as opposed to Welcome Break at Leicester Forest where we were timetabled to stop. Basically cause at 3.40am in the morning, for the south, and about 2.00am for the north, at Leicester Forest there is a Coffee shop if your lucky. At Watford Gap you could get food, and also not loose any passengers, as a few have problems with directions at Leicester Forest, once there on the bridge.