A lot of countries that had been conquered managed to evacuate a lot of ships, both merchants and warships, and kept fighting for the duration of the war. For example, the Greek merchant marine was very active throughout the war and there have also been memorable instances of Greek warships too. Destroyers like Adrias which sailed in Alexandria with the bow cut off by a mine and the British fleet formating in lines on the harbour's mouth (honour guard type of thing i guess, they had written the ship off and didn't expect it to come back), or Queen Olga which took part in a lot of allied operations in the med, like shelling the island of Pantelleria during the early stages of the landings on Italy, etc.
I wouldn't be surprised if Polish ships were operating under British control for the duration of the war, much like Polish squadrons in the RAF.
