why didn't we build it ourselves?
Maybe it has something to do with the fact that British government of the day was the same government that sold newest Nene and Derwent jet engines to the
Union of the Soviet Socialist Republics?
It is said that when Stalin was asked for permission to allow purchase of jet engines from Great Britain, he responded: "You can try, but no idiot would sell us that".
Yet that idiot has been found.