I also found an interesting site,
Military search and Rescue Statistics: 2007, with also a report on the first quarter 2008 on another link.
It indicates that there are 2 RN SAR bases (Culdrose and Gannet) and 6 RAF SAR bases (RAF Boulmer, RAF Valley, RAF Lossiemouth, RAF Leconfield, RAF Chivenor and RAF Wattisham). I know that this is old data (2007), but the representation in Table 2 makes for humbling reading. That's an awful lot of responses by all concerned: an average of 5 callouts per day
