I think Mrs Gale is the clue to this, it seems reasonable to think she was a friend or neighbour of Thomas and knew he was looking for a wife to take care of his children.
So her friend or sister back home has a daughter in need of a husband, with no chance of finding one in England in 1920, as the war, regrettably, meant that there was a shortage of eligible men, so a marriage is arranged, possibly with exchange of letters and photos, and Mrs gale testifying to Thomas's excellent qualities.
I had two aunts in this situation, both unmarried, and their diaries, which I should not really have read, suggests their mum spent a bit of time trying to arrange marriages.
Quote " I would rather die than marry mr xxxx"

Mike