Port Vale

Frith was appointed manager of Port Vale in August 1945. The 1945–46 season was uneventful and he seemed to settle into management quite well. In preparation for the first season of post-war football, he signed experienced forward Colin Lyman from Tottenham Hotspur for 'fairly substantial fee', full-back Garth Butler from Derby County, and half-back Norman Hallam from Chelsea. He sold goalkeeper Arthur Jepson to Stoke City for £3,750. However, after a poor start to the season, he resigned in October 1946 over a policy difference with the club's directors. He claimed the board refused to back his suggestions for new players, interfered in team selection and failed to grant him a three-year contract – claims which the club denied.^[6] The "Valiants" went on to finish the 1946–47 campaign in tenth place in the Third Division South under Gordon Hodgson.

Coventry City

After leaving Port Vale, Frith returned to Highfield Road as assistant to Dick Bayliss, and also played seven league games. Following Bayliss' death, Frith was appointed as manager of Coventry City in August 1947, remaining in that position until November 1948.^[7] He signed goalkeeper Reg Matthews but was sacked with the club in the bottom two.^[8] Coventry finished the 1947–48 Second Division season in tenth place, and went on to end the 1948–49 season just two points above the relegation zone under Harry Storer's stewardship.

Following spells in charge at non-league clubs Stafford Rangers and Rugby Town, he rejoined Coventry City as a coach and was once again appointed manager in September 1957.^[7] His side ended 1957–58 in nineteenth place in the Third Division South, and so were invited to become founder members of the Fourth Division in 1958–59. He then took the club to a second-place finish in 1958–59, four points behind champions Port Vale, his former club; City were therefore promoted into the Third Division.

His side flirted with the prospect of a second-successive promotion in 1959–60, but ultimately finished in fifth place. They failed to push for promotion in 1960–61, and ended the campaign in fifteenth place. On what was known as 'Black Saturday', 25 November 1961, Coventry were dumped out of the FA Cup by non-league King's Lynn, and Frith was sacked by chairman Derrick Robins.^[7][9] He was replaced by Jimmy Hill, who took Coventry to a fourteenth-place finish in 1961–62. He later managed Chelmsford City, and led the "Clarets" to second and fifth-place finishes in the Southern League in 1963–64 and 1964–65. He later worked as a teacher until retiring in 1977.^[8]