One Thousand Miles in One Thousand Hours

According to this site:

On June 1, 1809 Captain Robert Barclay Allardice undertook what was then the greatest sporting feat ever attempted - to walk one thousand miles in one thousand hours for one thousand guineas. Six weeks later, exhausted and on the verge of collapsing, he completed his challenge and instantly became the most famous sporting figure of Regency times.

The feat was later repeated by Bob Carlisle in Newton-le-Willows.