I know there was an outfit called Blue Air who used DC-4’s for holiday charters, from Manston I think. Dan-Air had their fingers in many pies in the late 60’s onwards with Comets, Boeing 727 and the like. All were well past their sell by dates. One 727 I flew in to and from Lanzarote had to stop off at Valencia on the way back to top up its tanks. Whether it was headwinds, or just cheaper fuel being the reason I’ll never know, but the diversion made us late into Gatwick, missing the last train home.