Jimmy Leadbetter was born in Edinburgh on 15 July 1928, the son of a local garage owner who had played for Bathgate. Jimmy played for Murrayfield Athletic until the age of 17, when he started his National Service in the Royal Artillery. Whilst in the Army he played for a Combined Services team managed by former Bolton and Liverpool player Johnny Wheeler. After leaving the army, he played for Hibernian feeder club Edinburgh Thistle, winning the Scottish Juvenile Cup, before turning professional with Armadale Thistle.
In July 1949 he signed for Chelsea, but failed to claim a place in the first team, playing just three games in three years. He was the first player to leave Chelsea after Ted Drake became manager, signing for Brighton & Hove Albion in 1952. He became a regular player at the Goldstone Ground, averaging a goal every four matches, which saw him established as one of the best wingers outside the First Division.
In 1955 Ipswich Town signed Jimmy for £1,750 and he made his Ipswich debut in the Football League Third Division South on 8 October 1955 in a 1–0 home win over Bournemouth & Boscombe Athletic. This was his only game until December, but he then took over from George MacLuckie at outside centre, earning a regular first team place. He continued his fine form at Portman Road and helped Ipswich win the division title in 1956-57 earning promotion to the Second Division.
Whilst at Ipswich, Alf Ramsey converted Leadbetter from an outside left to a more withdrawn left-winger role. He began to play deeper, threading through passes or providing crosses for the prolific goalscoring partnership of Roy Crawford and Ted Phillips. This was to be the prototype for Ramsey’s Wingless Wonders, with which he won the 1966 World Cup. Ramsey later admitted “Yes, he was Scottish, but I owed him so much.”
Ipswich won Division Two in 1960-61, earning promotion to the First Division for the first time in the club’s history. The following season saw the club win the First Division at the first attempt. Many of the goals scored by Crawford (33) and Phillips (28) in Ipswich’s championship-winning season were attributed to Leadbetter.
However, in October 1962 Alf Ramsey was appointed manager of the England, with Jackie Milburn replacing him as Ipswich manager. Milburn was unable to maintain Ipswich’s form, and in 1963-64 Ipswich were relegated back to the Second Division. Jimmy made 19 league appearances in 1964-65, with his final game being in the FA Cup on January 1965.