So, I'm thinking about a pre-SOE British counter intelligence agent. He could have been sent into Poland when things first started getting hot in order to meet with Jan Gorski, bring back info on the state of things to the crown. After the invasion they got separated, Jan fled to France to start the silent unseen, while my British agent is left behind with the Polish underground. Unable to escape passed the nazis he joins up with someone suggested to him by Jan, eventually leading him to the SZP or ZWZ. This is a really bareass skeleton of an idea here. Just throwing it out to see if it gets shot down. I understand if it's a little too far fetched.