Monarch of course went for the same, introducing a fleet of onetime Northwest 720Bs from the end of 1971. The 720B is essentially the same as a 707, with a series of structural lightenings etc to suit more medium-haul operations. They ran, mainly from across the ramp from Britannia at Luton, to the same range of Mediterranean etc holiday destinations and the scatter of off-season points further afield.
I wonder, had the 707 concept had worked for Britannia, if the company would have purchased some new aircraft
707 production was on its last legs by the time this trial ended, the world had moved on; Laker was getting the DC-10 and Court the Tristar by then. Both were really too big for the holiday flight market which, especially for Britannia witrh their approach of services from every significant UK airport, needed something smaller and more flexible, but with the range to reach the "4 hour" destinations like The Canaries or Cyprus. When the 757 came along 10 years later, that was spot on.