Thanks to all for your replies.
It appears that the Police units use a form of STASS then, but what about the North Sea operators who operate over some pretty rough waters every day of the year? Do they not carry STASS or HEEDS, or is it just the oil comapnies that make their staff wear rebreathers?
If the CAA wont mandate the use of EBS for these guys, I take it that the companies wont enforce the use of them unless the oil companies want them to?
It seems strange that the Police units appear to encourage the carrying, use and regular training of such equipment but not those that fly over water every single day?
I wonder if the Bristow SAR units carry something like STASS as do the military SAR units?
I find it strange that the CAA wont mandate these pieces of equipment for those who spend most of their flight time over water.