History / Seeking details of Polish Soldier - Carol Biscupec/Biskupec [7]

I am researching the military service of a relative's father an Englishman who served in WW2 in France. My man died a few years ago however his son remembers him talking about a Polish soldier who became a great friend of his father.

The only details we have is his name Carol/Karol Biscupec/Biskupec, who may have served with the Royal Engineers and who is believed to have joined the Paris Fire Brigade immediately after the war.

Can anyone help, please?