I may be wrong, but I'm pretty sure during the summer Britannia would use one 737 on the 2 x Schedule to belfast with 2x troopers to Germany inbetween. The last Belfast would get back about 2200, then it would do a night charter to somewhere in the Med.
I'm pretty sure there are not as many night flights, especially holiday charters, now as there were in the 70s and 80s.