The daughter of a Scottish surgeon, Margaret Macrae married Henry Mercer in 1878. However, he died shortly afterwards, and in 1881 she married Lewis Weedon, for many years a member of the committee of the Sussex County Cricket club. Margaret won many archery trophies with both the Brighton and Hove Archers, and the West Kent Archery Society. Having won the prize for the best score from 60 yards at the 1904 Southern Counites Championship at Beddington Park, Surrey, she enjoyed what was probably her first moment in the sport the following year when she won the Challenge Brooch for the Best Gold at the Grand National Meeting at Southampton, although she had won the Associated Clubs prize for the greatest number of golds at the 1892 and 1897 Grand National Meetings. At the 1908 London Olympics, Weedon competed in the Double National Round, and finished 14th out of 25 starters.