When these old posts pop up again it's an opportunity to check what fresh information may have come on line in the meantime. Did you decide on a location for the "golden mile". As I said in post #21, I understood the "golden mile" to run from Waterton Cross to the turning to Corntown at what I used to know as the "bottom of Crack Hill".
There's a motoring court case in the Glamorgan Gazette, 8 July 1927, which begins -
"Many people speak of the Cowbridge Road, from the Barry railway bridge to the bottom of Crack Hill, as the "golden mile", but as has oftentimes been pointed out in this column, this is wrong". I take the Barry railway bridge to be the bridge that crosses Cowbridge Road just before it hits Waterton Cross see
https://maps.nls.uk/view/102183681The Chairman of the Court, a Col. J I D Nicholl, J.P., took issue with this and remarked -
"It is not the Golden Mile. The Golden Mile is from the top of the hill to Pentremeyrick". This is supported by a more recent assertion in "The Legend of the Golden Mile"
https://glamorganstar.co.uk/the-legend-of-the-golden-mile/but it does recognise that opinions are divided.
You can see "Golden Mile" on this map
https://maps.nls.uk/view/102183708This was the site of the Golden Mile Barrow find/excavation, also referred to as "Twmpath".
So, given the confusion that appears to have reigned even at that time, which Golden Mile was the person who reported the "dray race" accident thinking of?