Funny thing is steam enthusiasts call engines 'she'. Even if they have a male name.
Revd. Awdry was a steam enthusiast back in the days when lines had closed and sheds railways left to fall into disrepair. People who were into railways were male and the books were written for little boys. Of course you wouldn't do it nowadays, but I can see how it happened. My Dad is a steam railway buff and I remember, as a small child in the 70s, people sympathising with him about having daughters - while we were stood next to him, FFS. 
(Actually our possession of X chromosones never stopped my Dad taking us onto footplates or engine sheds, as it happened - many an hour of my childhood was spent on railways.)
My Dad knew Revd. Awdry and by all accounts he was a nice chap. In the days when chaps were chaps and didn't think about equality for women.
The original stories were all based on real events - they were all about things that had happened, such as the cricket ball ending up on the trucks and being carried off by the train. The sort of stories steam enthusiasts would tell each other down the pub after a long day shovelling coal.
The one that gets me is the one about the Little Lost Engine. I welled up every time I read it to ds, as it is true - the Little Lost Engine really was forgotten when his railway closed and Revd. Awdry really did stumble across his shed, covered over by the weather washing soil over it, on a Welsh hillside. He's called Prince, and he was rescued and lives on the Ffestiniog Railway (last I heard). Awww...