Ebbw Vale, Gwent born inside left Les Boulter began his football career with Cwm Athletic in 1931 and was signed by Second Division Charlton Athletic in 1932, making his Football League debut against Plymouth Argyle in February 1933. After suffering relegation to Division Three (South) at the end of the season, Boulter was part of the team which completed a meteoric rise to Division One in two seasons, securing the Division Three (South) Championship in 1934-35 and a runners-up finish in Division Two in 1935-36. The Addicks amazingly challenged for the League championship in their first three seasons in the top flight, finishing as runners up in 1936-37 and in fourth and third place in the final two full seasons before the Second World War. Boulter departed The Valley in February 1939, signing for Brentford for a £5,000 fee, after making 176 appearances, scoring 28 goals during his time with the club.
Signing on the same day as forward Tommy Cheetham (who had signed from Queen’s Park Rangers), the pair made their debuts in a 4-2 defeat to Aston Villa on 7th February. He made his Wales international debut the next month, scoring in a 3-1 victory over Ireland at The Racecourse Ground, Wrexham, but it was to prove his only international for his country. He scored twice in 19 appearances for Brentford, but his career was cut short by the abandonment of peacetime football in September 1939 after the outbreak of the Second World War. During the War he made guest appearances for Manchester City and Blackpool, and after its conclusion Boulter dropped into non-league football to sign for Southern League side Yeovil Town in 1945. He scored five goals during the 1947-48 season, helping The Glovers to an eighth-place finish, before his retirement.