The answer is the 1st Battalion Royal Scots Fusiliers. The Royal Scots Fusiliers (RSF) were a Territorial Army (TA) unit of the British Army, serving in Aden from December 1961 to February 1963.
The RSF served in Aden from December 1961 to February 1963. In the summer of 1962 the TA was expanded to provide a third field army, and the 1st Battalion was sent to Aden as part of the 1st (British) Corps, under the command of General Sir John Harding. The 1st Corps was responsible for the defence of Aden and its immediate hinterland, which included the oilfields of the Jubail and Hormuz oilfields.
The 1st Corps was commanded by Lieutenant General Sir John Harding, and consisted of the 1st and 3rd Armoured Division, the 1st Infantry Division, and the 1st Corps Troops (TA). The 1st Corps was formed in November 1961 and the 1st Infantry Division was sent to Aden in January 1962.