Margaret McDowall had the following podium finishes at major championships: 1st in the 1954 British Empire and Commonwealth Games 3×110 yards Medley Relay (with [Elenor Gordon] and [Margaret Girvan]). In the 1954 British Empire and Commonwealth Games 110 yards backstroke McDowall finished fifth. In the British Empire and Commonwealth Games she competed for Scotland.
|1952 Summer||16||Helsinki||Swimming||Women's 100 metres Backstroke||Great Britain||GBR||7|
|1952 Summer||16||Helsinki||Swimming||Great Britain||Final||7||1:18.4|
|1952 Summer||16||Helsinki||Swimming||Great Britain||Round One||Heat One||3||QU||1:17.5|