Too early spec for the Metrovick or other jet trials, as suggested above I'd guess a bravado piece by someone with a very large and public willy. I can't see any reason to believe that all engines aren't feathered,and if we discount hidden jet units that's the position.
Not at all surprised, given the risks those boys took on a daily basis what is the big deal about feathering all four?
Perhaps we've al got a bit too precious regarding slightly adventurous pranks these days.
'fact is, I know we have.
So bless'em, whoever they were, and let us thank God there used to be aviators with balls. And a proper sensavumour.