Lee changed the team's formation from 4–4–2 to 4–3–3 for the 1973–74 campaign, hoping that this would allow Horton more room in the centre of the field. However Vale's form suffered, and Lee was replaced as manager by Roy Sproson in January. Vale finished the campaign one place above the relegation zone, though were seven points clear of the relegation zone. Horton played 46 games, scoring four goals. Vale missed out on promotion by just four points at the end of the 1974–75 season, as Horton hit thirteen goals in 47 games, leaving him one goal behind top-scorers Ray Williams and Terry Bailey. He hit four goals in 35 games in the 1975–76 season, including both of Vale's goals in a win over Millwall at Vale Park. Much to the disappointment of Vale supporters, he was sold to league rivals Brighton & Hove Albion in March 1976 for a fee of £30,000. In total he spent nearly six years with Port Vale, scoring a total of 37 goals in 258 games in league and cup competitions.