1911-1914: Circuit of Britain Air Race
An early air race organised by the Daily Mail newspaper in England.
Here is some movie footage…
Daily Mail – 1913
“The first prize is the sum of £5,000 to the first person who shall
pilot a waterplane of entirely British invention and construction
round England, Scotland, and Wales—and, so far as Ireland is
-concerned, within one mile of Kingstown Harbour—in seventy-two
continuous hours, starting and finishing at a point to be agreed upon
near the mouth of the Thames.”
Ref: Flight, April 5, 1913
References
Circuit of Britain Air Race (Wiki.)