* hen Kathleen Thomas stepped into the Bristol Channel at 4.15 on the morning of September 5, 1927, nobody thought she would triumph in such a treacherous stretch of water.
Covered in lanolin - scant armour against the chill temperature - the 21-year-old intended to swim from her home town of Penarth to Weston-super-Mare, a distance of around 11 miles as the crow flies but more than 20 once the Channel's double-crossing currents are taken into account.
The Severn Sea, or Mor Hafren, was considered deadly and omnipotent.
Men had tried and failed to swim it, many others had died when their boats were turned over. A slip of a girl getting to the other side? Was this some kind of joke? Indeed, after the South Wales Echo ran a story detailing Kathleen's courageous plan, the paper was compelled to underline its scoop.
'Miss Thomas Confirms Echo Report', said the headline.
The story read: Miss Kathleen Thomas, the Penarth lady swimmer, whose decision to attempt the Bristol Channel was exclusively reported in yesterday's South Wales Echo, reaffirmed in an interview today that our report was correct in its entirety.
Doubters left standing on the shore, Kathleen struck out and seven hours and 20 minutes later she arrived on the beach at Weston, to the applause of West Country folk who lined the edge of the water to greet the girl from Wales.
After a hot and cold bath, a rest, and a good fish lunch in one of the town's hotels, Kathleen returned home a celebrity.
More than 80 years later, standing on the cliff tops of Penarth, looking at the chill grey waters, I realised what a very real triumph this was at a time when women were called harlots for baring their knees in bathing suits.
A keen swimmer myself, I had phoned the coastguard to ask if it was safe to swim close to the shore on Penarth beach.
His response was more or less: 'You need your head examining if you go in that water.' So when I heard that two years after Kathleen's victory - the town's pier now has a plaque in her memory thanks to the efforts of her relatives - a 16-year-old school girl called Edith Parnell also swam the Channel, I was captivated by the bravery of these two young women.
It's fair to say I became obsessed with them. I was in and out of Penarth Library searching through back copies of old newspapers for any information I could find.
What kind of young women living in a small Welsh town would do this? Where had they ended up? I discovered Kathleen had become an 'It Girl' of her day, welcomed at swimming galas as Men of Harlech played her in.
Then I found a picture of Edith in a local history book. She had a dark bob and stood in a Wolsey bathing costume alongside her father on the beach, the jut of her jaw engagingly determined.
There were little clues - 'I should have liked to do this last year but Mother and Father wouldn't allow me' - that Edith was a focused character but there was something isolated about her too.
Perhaps her desire to achieve was scorned in a town where the newspaper's most popular feature was a string of gossipy anecdotes that verged on libel.
She reminded me of the actress, Melanie Lynskey, playing Pauline Parker in Heavenly Creatures, the same dark insouciance.
Edith Gertrude Parnell had the look of a girl intent on doing something nobody thought she would.
When I sat down at my computer to make a story of these swimmers, I was cocksure enough to think I could string a sentence together and that any tale forming in my head would roll out reasonably well onto paper. …