Brigadier Dennis E. O. Thackwell was born in Poona, India, on the 18 March 1909. His father was Brigadier O. M. R. Thackwell R. E. who had spent the major part of his Service life in India. He went to Rosall School in Lancashire, UK, and completed his academic education at Corpus Christi, Cambridge. On 31 January 1929 his military career began when he was granted a regular army commission as 2nd Lt. Royal Engineers at Chatham.
In World War II he served firstly in Survey of India and then in various military roles and latterly as Assistant Director Survey in G.H.Q., India, in the 4th Army and in the 12th SEAC.
In 1946 he returned to civil employment in Survey of India. From 1948 to 1963 he was in charge of divisions of the Ordnance Survey UK and in 1959 was promoted Brigadier and appointed Director Map Production OS, Gazetted C.B.E. in January 1963 and retired in June 1963.
In addition to his distinguished service to military and civilian survey and mapping, he served the cartographic community in many ways such as by his work on the Royal Society Cartography Committee, on the UK committee devising a new specification for the 1:1 Million Map of the World (1962), on the Executive Committee of the newly formed ICA and as the founded President of the British Cartographic Society in September 1963 and on to 1966. On 6 September 1983 at the Royal Society in London, the President of the ICA, Professor F.J. Ormeling, presented him with the Honorary Fellowship of the Association and the following is an extract from his address:
“Brigadier Thackwell was elected President of the Association by the Second General Assembly in Edinburgh in 1964 when the Association was five years old. He succeeded Professor Imhof, first President and one of the founder members of the ICA. His administration was soon characterised by a series of actions and decisions which strenghtened the Association and resulted in a healthy growth of prestige. To minimise confusion in allied disciplines such as geodesy, photogrammetry, graphic arts, geography as to aims and objectives of the Association, Thackwell started to stake out the area of interest, the sphere of influence of cartography. He made it clear that cartography had a specific problem area, distinct from, but closely related to surveying and photogrammetry. He introduced the Technical Meetings between the 4-yearly conferences, the first of which was held in Amsterdam in 1967. Under Thackwell’s administration the first three commissions (Education, Terminology and Automation) started their work. Together with de Brommer (France), Chairman of the first mentioned commission, he initiated a series of successful UNESCO conferences on Education in Cartography in Paris. Further it was Thackwell who managed to bring the extravagant ambitions of the Commission on Terminology to workable dimensions, thus laying the foundation of the Multilingual Dictionary of Technical Terms. Together with Professor Boesch, Secretary General of the IGU, he strengthened the relationships with the geographers by introducing joint sessions on subjects of common interest during overlapping conferences.
The years of Thackwell’s Presidency in many respects were of a decisive nature for the Association. His cool leadership and clear judgement inspired confidence, attracted new member countries and brought outlying members into active collaboration. As a token of gratitude and respect the Executive Committee upon recommendation of the Committee for the Selection of Award Recipients decided to confer the Honorary Fellowship on Brigadier Thackwell. I am honoured to announce this decision.”