The ultra long runway was intended for the Brabazon and any future long range piston engined aircraft. It was believed that the take off performance would always be poor and a long runway required.
For the same reason they demolished the pub at the end of Filton runway so they could extend it.
The link between Thurleigh and Twinwoods was to be a taxiway. The tale always told was that it was to facilitate getting full size aircraft to the wind tunnels.Then the technology overtook the idea.
The whole thing was part of an idea to build a National Aeronautics Establishment but Farnboro and other politics scuppered that idea. Bloody Cody's tree was more important.
Ah Bedford ATC "the cowboy outfit I'd always wanted for Christmas"