Before this thread gets out of hand it might be useful to examine the logic of what is being proposed.
One of the tenets of CAP 1145 is that the protection of passengers against known threats should be improved. One of these threats came to light (more than a decade ago) when the 332-like helicopter capsize evacuation trials took place in Canada (references in the CAP). This trial established that evacuation time from a capsized helicopter could exceed the breath hold time of some of the occupants. Subsequent research clarified that the average breath hold time in water temperatures experienced in the North Sea, Canada, etc was about 9 seconds.
The oil companies acted upon these reports and, to increase the breath hold time above the evacuation time, issued their passengers with re-breathing devices (which could contain an air reserve). These re-breathing devices required the passenger to fit the device before water entry and fill the 'lung' by breathing into it before submersion. Such devices could be classified as Category B devices under the guidance contained in CAP 1034. Category B devices are effective in cases where the aircraft is ditched (as opposed to crashed - known euphemistically as water entry).
However, closer examination of the data appears to show that the incident of fatalities in 'ditching'/'water entry' incidents/accidents are associated with water entry and not ditching (it is probably the case that there has never been a fatality associated with a ditching). Whilst breath hold with respect to ditching appeared now to have been addressed, the complexity of fitting the re-breathing devices and a requirement to fit after a water impact - i.e. under the water - required a more robust device. This water entry standard (which is probably associated with a device containing gas under pressure) is described in CAP 1034 as a Category A device.
The objective set by the CAA in CAP 1145 was that, from the date specified, all passengers should be in a situation where breath hold time exceeded evacuation time for a capsized helicopter under water entry conditions. This translates, in prescriptive terms, to the necessity for passengers to be equipped with a Category A EBS. Up to the time that this situation obtains, no passenger must be in a seat where the time to evacuate will exceed the breath hold time under water entry conditions.
In another element of the same thread, and in order to maximise the time-to-capsize under ditching conditions; from the date specified, a helicopter will not be permitted to operate over sea conditions that exceed the limit of the ditching approval and no 'normal' operations will be permitted in conditions exceeding Sea State 6 (significant wave height of 6 metres).
Now fill your boots.
Jim