BA was a combination sequentially of Tristars, 767's and 757's operating BOS, JFK and EWR in various guises. Think the similar BHX experiment added YYZ to the triangle.
Air Canada to YYZ was trumpetted at one point in the press as it was operated by 742 for a while. And a direct 762 service to YHZ if I recall
United IAD was 762 starting in the old Saul Bass livery.