I've always understood that the Spey was chosen solely to give UK manufacturing input and it did adversely affect performance - "lots of money for a worse aeroplane."
However I've recently read that without the Spey - or more accurately, with the original engines - we couldn't have used it on our carriers.
This goes against the accepted story but if it's true why isn't it better known?
Bear in mind - "I know nothing" - it's only something I read somewhere fairly recently.