1. Tuna, Sealion, Graph, Uredd, O15 and Junon.
2. It is of interest that of the thirteen independent ships which sailed for North Russia, four were sunk, one was wrecked, three turned back but five got through to Archangel.
3. Ex-P47
4. Cortellazzo made the open Atlantic but ran into convoy KMF4 and was scuttled after being engaged by its escorts.
5. It is of interest that A(S) held that Clyde should have left her bombing restriction area to pursue but he does not seem to have done anything about extending or enlarging it at the time.
6. Barb, Blackfish, Herring and Shad.
7. The main German destroyer force was back in harbour by this time and these must have been patrol vessels.
8. Polish Sokol and Dzik, Netherlands Dolfijn and Norwegian Uredd.
9. These totals do not include the losses of Netherlands submarines operating in the Far East.
10. A surface speed of 18 knots and a diving depth of 500 feet.
11. All pre-war designed submarines, including the early T-class, had all-riveted hulls. The first war production submarines had welded frames and riveted plates and the later submarines of all classes were all welded.