East Malling Research pomologist Tony Webster was also given honorary life membership.
Dixon has served the society since the 1970s with convenorships of symposia and as an author, editor, commission chairman, member of the executive and governing council member. Most recently he served as internal auditor. He represents the UK on the ISHS council.
The society started in 1864 at an International Horticultural Congress held in Brussels and now has 7,000 members and organises 30-40 symposia a year, with proceedings published as Acta Horticulturae.