I did some survival gear testing at Lee on Solent, we checked both the then current immersion suit against the aircrew one man dingy.
They rigged the pool which was used for ejector seat training with fans which blew a 14 knot refrigerated wind across the top of the almost freezing water in the pool, myself and a mate were the first two to go up, we got a neat tot and I got to stay there for a couple of weeks acting as handler to the blokes in the water.
From memory we did 3 hours in/on the water for each bit of kit and then had to write up our preferences. The immersion suit leaked at one cuff because all of the monitoring wires (ECG etc.) came out through it. We wore Nos 8's with Submariners Sweater for both tests, for the dingy test we had to go into the water first and stay there for a minute before climbing into the dingy. Cold doesn't even begin to describe the conditions, the two research Docs. conducting the tests reckoned there was a big safety margin as you could live for 3 minutes in the water. We had to pull a couple of blokes out and resusitate them, one in particular I remember went blue and had to be pulled out as soon as he entered the water.
As I say we got a neat tot, we also had to swallow a small transmitter wrapped in a condom type thing which monitored our internal tempeture, we got 10 shillings for returning it, so that it could be reused. The joys of crapping into a plastic bag and then sorting through for the transmitter I'll leave to you imagination. Still you could buy a few wets for 10 bob in the early '60's.
Myself and a mate had volunteered for everything going trying to get away from the Comcen at Dolphin. The kindly CRS at the time put us in for this in an effort to curb our escape efforts. As it happened Ali's draft came through almost as soon as we got to Lee and mine followed a couple of weeks later.