Interesting the find of Ruby (Rupert) Pettit - I note he didn't marry until he was 39 and that he and wife Ethel Bass had no children. He lived in Camberwell in London in 1920 and then appears to have returned to Suffolk where he married Ethel in 1927. They then lived in Greenwich from 1928 until 1937 but by 1939 were back in Suffolk. He died just 2 years later in 1941.
He served as a Gunner in the Royal Field Artillery and when he enlisted on 5/5/1915 his address was 26 Deptford Bridge, Greenwich and he was working as a Barman. Quite a change from the occupation that he had in 1911. When demobbed 15/4/1919 he gave his address as his fathers in Stowmarket though clearly returned to London as living at 121 Albert Road, Camberwell the following year.
In view of your find one can't help wondering if he was indeed the culprit and ran off to London to escape responsibility (or are we maligning an innocent man).
Certainly, I feel sure that a Mr. Pettit was indeed her father.
Annette