Tallon worked at Leyland Motors, where he joined the Amalgamated Engineering Union (AEU). He held a variety of posts in his union branch and, later, at district level, and was elected as secretary of the joint shop stewards committee at Leyland, then became a full-time regional officer for the union.
In 1952, Tallon was elected to the executive council of the AEU. Although this was the peak of his career in the union, he came to greater prominence representing the AEU at other national bodies. He served on the executive of the Confederation of Shipbuilding and Engineering Unions, and was its president in 1966/67, while in 1957, he was elected to the General Council of the TUC, holding his seat until his retirement in 1967.
- Trades Union Congress, "Obituary: William Tallon", Annual Report of the 1979 Trades Union Congress, p.361
|Trade union offices|
| President of the Confederation of Shipbuilding and Engineering Unions
1966 – 1967