If cutting metal is the definition, the daddy of them all has to be the VC-7/V.1000, whose prototype was apparently nearly complete in the sheds at Wisley when the project was cancelled
Interestingly, much of the construction of the V1000 took place at Vickers' shadowy Foxwarren site (where the prototype Viscount and Valiant were built), with final assembly at Wisley.
Whether the aircraft would ever have been a commercial success is debatable, with the V1000 suffering from the same obsession with short-field performance that doomed the VC-10.