Walpole started his career in aviation by joining the RAF in 1952. In his four years service he served as an operational fighter squadron pilot, flying Meteors and was also a member of the Fighter Command formation acrobatic team, giving displays all over Europe.
In 1956 he joined BOAC later to merge with BEA and become British Airways. Initially as a First Officer on the Argonaut fleet and later he was made the first training co-pilot in BOAC and in 1971 he was promoted to command becoming Fleet Captain of the 707 Fleet in 1972.
In 1975 he commanded the Boeing 707 aircraft used for the Royal Tour to the Far East which Her Majesty the Queen undertook and a year later he transferred to the Concorde Fleet. In 1977, he commanded the Concorde which flew the Queen from Barbados to London and the first supersonic commercial service from London to New York. His achievements were recognised in 1978 when he was awarded the Britannia Trophy, presented by HRH Prince Charles, the Prince of Wales, for his work on the launch of the Concorde New York service.
In 1982 he became the General Manager Concorde Division and was responsible for all aspects of British Airways Concorde operations, from marketing and advertising to control of the fleet's day to day operations.
His achievements in aviation were again recognised in 1983 when he was elected a Fellow of the Royal Aeronautical Society and two years later he was granted the Freedom of the City of London. In 1988 he became an Officer in the Order of the British Empire in The Queen's Birthday Honours List.