I helped with this query when it was first on the Harrow Facebook page.
There is a single Agnes Foley in Harrow area in 1939 born 1905. She married in 1946.Marriages Jun qtr 1946 Bradshaw James Foley Agnes Stepney 1c 331You may already have discounted her as I realise she does not match the age 19 but family information is often proved false.ADDED Possible birth registrationBirth Mar qtr 1905 Foley Agnes Mothers maiden surname PIGGFORD Chester le S. 10a 578
Death Sep qtr 1914 Foley, Catherine age 40 Chester-le-S. 10a 643
The last thing I will share with you is that on the letter from The Adoptions Society to my Nan was that he had been baptised on 1/1/1938 at a church in North Harrow. Alas we have been able to trace this either.