Barnes Wallis designed an RPV called Wild Goose which was tested at Predannack in Cornwall just post war. This used its swing wings for pitch and roll control too. Here it is on its launch dolly.
Due to the huge loss of life on the Dambuster raid, Wallis insisted on testing with RPVs first, for fear of any further deaths of aircrew due to his designs.
Wild Goose led to the Swallow design which, needless to say, got cancelled:
some other concepts like for example variable wingspan or variable wing area were tested in civil aviation
You could argue that when any modern airliner lands with its slats and flaps out, that it is making use of variable wing area.