WWII air/sea rescue craft

Here's another query for you old hands. Can anyone identify the class of 'yacht' that the RAF used to drop from aircraft on air/sea rescue missions.
Saw one beached many years ago on the West Coast of Scotland. It had a plywood hull shaped not unlike a cigar - 'O' shaped cross section. And was about 18 foot long offering accommodation for 4 in comfort - 6 in cramped conditions. It had a demountable mast and a simple gunter rig.
For some reason deHavilland scratches the back of my mind.
Any takers ?

 

The british boat was by Uffa Fox
http://www.uboat.net/allies/aircraft/warwick.htm

the American boat was by higgins
http://www.pbyrescue.com/Photos/2ERS0000/796.htm

 

You're a man of the first water Jeharidiman... I can now sleep in peace. Many thanks for instant reply. The version I saw I believe was the Uffa Fox design. Though I must admit over the passing years I began to believe I had imagined the whole episode. Ugly but sturdy craft - and damned water tight. But at least I now know it was for real.