Winnie's birth registration hasn't been found. She was said on the 1911 census to have been born in Mongomeryshire - the only possible contender, Winifred Jane GREEN was registered at Atcham (which covers part of Montgomeryshire) in Q3 1908 but mother's maiden name is given as FORRESTER.
The 1939 register entry gives Winnie's birth date as 1 August 1907.
The middle name BLATCHFORD appears on Winnie's death registration entry.