Future Games question

[macfan 57]

I noticed that Martin Birch is listed as producer and or engineer on all Fleetwood Mac albums from "Then Play On" through "Mystery To Me", except for "Future Games". Martin Rushent is listed as the engineer on this album. Does anyone know who Martin Rushent is? Is it possible that Martin Rushent is some sort of a pseudo name for Martin Birch? I just think it's strange that Martin Birch was involved with all of these albums except this one. I don't even remember Mick mentioning Martin Rushent in his book.