For those who wish to read about Airborne Lifeboats there is a 20 page booklet called Unsung Heroes of RAF Air Sea Rescues on this page about half way down http://www.aviationmuseum.net/the_Shop.htm

The booklet charts the rise of the Mark I lifeboat fitted to Hudsons and then the next mark to Warwicks and so on to Lancasters and Shackletons.

Better still pay Flixton Aviation Museum a visit they have a small museum dedicated to ASR which is brilliant