John was about 15 when pictured in 1946, so born about 1930.
Name: John Robinson Mother's Maiden Surname: Brereton Date of Registration: Oct Nov Dec 1929 Registration district: Birkenhead Registration county: Cheshire Volume Number: 8a Page Number: 681
There was another John H Robinson (mother Edge) that was born this year, but that John died the same year.
Family lived in a caravan before emigrating to Australia with his family after WW2 (in the late 50s), to get away from his in-laws. However, they followed him there a few years later. The Australian tourist office made a promotional film about them and some of the Dittmer family went to a special viewing at a cinema in Liverpool about 1964/5