From 6 July 1949 until 18 March 1950 he was aide-de-camp general to the King. On 18 March 1950 Barker retired from military service, at the age of 55, after a thirty-seven-year military career. He did, however, maintain his links with the army and was, on 1 January 1951, made Honorary Colonel of another TA unit, the 286th (Hertfordshire and Bedfordshire Yeomanry) Regiment, Royal Artillery, holding this post until 31 December 1962. He was Deputy Lieutenant for the county of Bedfordshire from 12 July 1952 until 20 April 1967.