This is from the Diamond Jubilee website:
http://www1.thamesdiamondjubileepage...ticipants.aspx
"Built in 1936, she is one of only 22 100-Class High Speed
Launches that were used by the RAF to rescue World War II
airmen from the seas. The launches operated from various
bases around the coast of Britain and saved more than 13,000
lives during the course of the war. In 1993 she was spotted and
bought by an enthusiast who began an intensive and thorough
restoration following which she was re-launched by HRH Queen
Elizabeth the Queen Mother in July 1996."
The link has more info on the other ships including some Dunkirk "little ships".