[6][7] Clegg came to prominence in the run-up to the 2012 Summer Paralympics, coming second in the British Swimming Championships of 2012 in the S12 100m butterfly.

[5] In the 2012 British International Disability Championships, he also posted strong results in the S12 50m and 100m freestyle events, with a time of 26.36 in the 50m.

[5] His events in the 2012 trials, saw Clegg being selected for the Great Britain team in the 100m butterfly and 50m and 100m freestyle for the 2012 Summer Paralympics in London.

[5] Clegg was joined in the Great Britain squad by his older sister, Libby, who is also visually impaired.

[9] In the latter stages of the Games he also qualified through both his heats in the freestyle events to challenge in the finals, but failed to win a medal in either.