Mixed fortunes & death
Although Oswald had still been a teacher when he enlisted, by the early 1930s he had become a commercial traveller and the family had moved to 10 Friary Road, Acton, which is where they were living when, in 1934, John declared himself bankrupt; it is more than likely that this was as a result of the Great Depression of the early 1930s, Britain's largest and most profound economic depression of the 20th century. Proceedings took place at Brentford and Oswald was eventually discharged in 1936.
In the late 1930s the Electoral Register shows Oswald and May at various addresses, two of them - 74 Elgin Avenue (left), Paddington and then 28 Chevening Road, Brondesbury Park (right), in NW London - being multi-occupancy at that time, whilst still being registered at 10 Friary Road (centre), together with their son, Morgan, their daughter, Mary, and their son-in-law, Frederick Louis Halliday.
I believe Oswald (senior) died in 1950, aged seventy-eight; the death of John O. Owen, aged 78, [Ealing 1950, 4th qt] appears on the General Register.(pictures courtesy of Google)