Born in Newport in 1909, Peacock was educated at St Woolos School and then Municipal Secondary School. From school he became an apprentice engineer before then joining the Monmouthshire Constabulary as a police officer. He joined the British Army in 1943, remaining in the Forces until 1946, holding the rank of Major on demobilisation. He was seconded to the Allied Military Government for Germany, where he served for 11 years. On retirement he moved to Jersey, dying in France in 1996.

Peacock was first capped for Wales against Scotland on 2 February 1929 at St Helens. Wales beat the Scottish team, and in doing so denied the Scots the Grand Slam. Peacock scored a try on his debut and was selected to play in the next two games of the Championship under the captaincy of Guy Morgan. The next season Peacock was not selected for the opening game of the 1930 Five Nations Championship against England, but again was selected for the remaining games against Scotland, Ireland and France. Although losing to Scotland, Wales won the next two games. During the game against Ireland, Peacock scored a joint try with Swansea’s Howie Jones; both men dived for the ball and the referee could not decide on the actual scorer. The record books show the try as a joint score. The final game of the tournament was against France and Wales won an overly violent match to finish the Championship in second place behind England. This was Peacock’s last game for Wales.