He spent much of his time developing the nascent Welsh Office, creating a new civil service structure in Wales and seeking to build the economic base. This included the opening of the Anglesey Aluminium smelter at Holyhead in his constituency. In 1967, Hughes was successful in securing that the Royal Mint be located at Llantrisant in south Wales rather than in Scotland or Durham, as argued by his cabinet colleagues William Ross and Anthony Greenwood respectively. The episode was regarded as enhancing the stature of the relatively new Welsh Office, as well as strengthening Hughes's position in the Cabinet.