Whisky Galore Easter Egg - Author As Actor

The following is mentioned in a number of Film Guides, and is not an original. But you have not mentioned it. So here goes.

Whisky Galore is the story of a Ship that gets sunk in WWII while it is carrying Whisky past a Scotish Island whose pub has run out of whisky. The Islanders (after the Sabbath) "rescue" some of thw Whisky, and then have to hide it from the Revenue Men.

The Captain of the ship that sinks is the author of the book on which the Movie is based. I think (from memory) it is Sir Compton Mackenzie.