Hi I am doing some research on the development, deployment and use of bathythermographs in WW2. I have some good stuff on the US side, the BT being a US product. But aside from a couple of files at The National Archives I have found very little on RN use. 50 submarine versions were ordered for subs in or going to the Far East. As regards the surface vessel towed version some limited trials were done near Russia in the Arctic and some off the Hebrides. So far nothing on actual deployment on RN ships. They were issued to RCN ships but were not thought of much value in he difficult Canadian waters. Anyone have any additional information or sources they can suggest please?