« Reply #4 on: Wednesday 16 April 14 20:21 BST (UK) »
You definitely need to ask for family stories to try to narrow down the place where your ancestor was born. There are no official online records for German bmds - this information is either gained by visiting the relevant town archives in Germany or writing to the relevant church - all cost money.
The Morman church has filmed some church records which they are allowed to use outside of Germany. You can discover if there is/are any to view by looking in the familysearch catalogue. If there is then you locate your local Morman FHS and order the film number for viewing at a modest cost. It's best if you know the birth town/village of your ancestor, otherwise it's like looking for a needle in a haystack. I clicked on "Keyword" (see the below webpage link) and entered "Poland" as a search option and got a page of results
https://familysearch.org/eng/library/fhlc/I don't know the circumstances of how your ancestors arrived in the UK but there are a list of ships on this page which arrived in Liverpool together with a list of each Polish passenger. I don't know whether the mother was pregnant at the time of arrival but if she was she could have been on one of the ships.
http://www.polishresettlementcampsintheuk.co.uk/passengerlist/shipsindex.htmfrom 1917 every "Alien" (= foreigner) was issued with a registration card and even in 1946 your ancestor would have had to have carried an Identity Card. My ancestor's documentation shows the full names of the "Alien" and also has the town of origin plus parents names.
Perhaps he was one of those Poles who enlisted into the British Army/airforce - if you Google/surf you'll see there's some information on what's available and what is not.
Aberdeen: Findlay-Shirras,McCarthy: MidLothian: Mason,Telford,Darling,Cruikshanks,Bennett,Sime, Bell: Lanarks:Crum, Brown, MacKenzie,Cameron, Glen, Millar; Ross: Urray:Mackenzie: Moray: Findlay; Marshall/Marischell: Perthshire: Brown Ferguson: Wales: McCarthy, Thomas: England: Almond, Askin, Dodson, Well(es). Harrison, Maw, McCarthy, Munford, Pye, Shearing, Smith, Smythe, Speight, Strike, Wallis/Wallace, Ward, Wells;Germany: Flamme,Ehlers, Bielstein, Germer, Mohlm, Reupke