[Leendert]

Paul,

A personal account on Operation Mainbrace here: http://thebrownshoes.org/content/harley-d-wilbur

Scroll down to the Mainbrace diary.

There's also a wikipedia page about Mainbrace

And you'd like to watch
http://www.britishpathe.com/video/exercise-mainbrace

Regards,

Leendert