During the Battle of Britain many pilots ended up in the sea. This was normally a death sentence, because although Britain did operate some Air Sea rescue capability, it was spasmodic and not very efficient. It was hoped that pilots landing in the channel would be spotted and picked up by passing ships, due to the weight of traffic in the area.
It was a fact that you had a much better chance of being picked up by the Germans. In fact Luftwaffe air crew were more likely to be picked up as well, simply due to their equipment. The biggest fault was with the life jackets. British pilots had to inflate their life jackets by blowing into them. Not something easy to do when your plane has been shot down, and you're dealing with the stresses of that, plus the freezing cold and having to swim in full clothes. In comparison the Germans had a small cylinder of compressed air that could be quickly used to fully inflate the life jacket. Equally the German aircrew were issued with fluorescein, a chemical compound that would produce a slick of bright dye to mark the location of the airmen.

Being spotted and staying afloat were only two small parts of the challenge, you still needed to be picked up, or the cold sea would still kill you. Here again the Germans were miles ahead of the British. They operated silver painted HE-115 float-planes with Red Crosses instead of black ones. The HE115 was used for a variety of other tasks, and would be attacked if spotted. But the silver Red Cross plane's were left alone.
These operated with impunity over British waters, until one fateful day a pair of RAF pilots spotted a rescue HE115 being escorted by BF109's. Deducing that the plane was up to no good, hence the escort, they attacked. From then on the Luftwaffe planes flew with normal markings and camouflage.
During 1940 the RAF began to organise a more coherent air sea rescue service, helpfully prodded along by Air Marshal Sir Arthur Harris, who wanted more of his crews to be rescued from the North Sea. Eventually in 1941 the RAF Search And Rescue Force was formed. It still exists today, and I suspect most of you in the UK will have been to the seaside and seen a bright yellow Sea king of the the SARF flying overhead.
It operated a variety of planes to search and rescue pilots. But it also manned High Speed Launches. The first of these was designed by Fred Cooper, the man behind one of Donald Campbell's early boats. When they were first built in the mid 30's they were the fastest craft at sea. However they were badly designed for rescue work, and later a much better design came from Hubert Scott-Paine, a winner of the Schneider trophy.

These were as fast as their predecessors, but were much better at the rescue role. They also mounted a pair of .303 machine guns in turrets for self defence. Some of you might question arming of a rescue boat. However the Geneva protocols allow for rescue craft to be armed, as long as they don't mount a weapon forward of the bridge. The weapons were there for self defences against German aircraft which were the only thing that was liable to be able to catch them. And wouldn't have the ability to accurately identify them.
On August 19th 1942 14 HSL's responded to some of the 47 Mayday calls from the Dieppe landings. After a an action that can only be described as disastrous (which I'll cover next week), several reports and studies were written. One pilot, whom had been picked up by the HSL's stated:
"There can be no question as to the bravery of these men of the Air Sea Rescue Service who were often working within sight of the French coast. For myself, I would rather meet a FW 190 head-on in my Spitfire than meet one from a rescue launch."

Following all these reports armour plate was made available to help protect the HSL's and a large increase in their fire-power, in the form of 4 extra .303 machine guns in twin mounts, and a 20mm Oerlikon cannon on the rear deck. In this form the 70 or so HSL's served until the end of the war.
From its first operations to the end of the war, the SARF rescued over 8000 military and 5000 Civilians.