Willi,
Pre-COVID I did some research into the various records concerning POWs held at TNA, and at that stage there was no index of escapees. The man I was looking at had been on the escape committee in the German POW camp where he spent most of his time, but his name did not occur in the WO 208 series -special questionnaires for those who escaped or were on escape committees. He completed a very detailed answer on his questionnaire in WO 344, complete with plans of tunnels and the numbers of men who escaped through each.
WO 416 and WO 392/1 contain indexes of POWs generally, and you can find some of the ICRC Camp reports in WO 224 and FO 916. Obviously many more men escaped from the Italian POW camps, but of the 170,000 British and Commonwealth POWs in Germany only around 1,200 manged to escape.
Since you father escaped to Switzerland, don't forget to check the Foreign Office series as there is bound to be some correspondence between the British Embassy in Berne and London concerning those interned by the Swiss.
