Weston was educated at Sherborne School and Worcester College, Oxford, taking a double first in Classics and Philosophy.
Weston joined the Diplomatic Service in 1962, and was posted to Hong Kong (Chinese language student); and subsequently to Beijing, to Brussels EC (with the UK Permanent Representation to the European Community) and to Washington DC.
In 1990, he was the British official negotiator on the Treaty on the Final Settlement with Respect to Germany (for which he received the German Order of Merit, with Star).
John Weston was a Non-executive Director on the Boards of several companies including British Telecom 1998–2001,and Rolls-Royce Group plc 1998–2005.
The first collection of his poetry, Chasing the Hoopoe, published by Peterloo Poets in August 2005, was described by Harold Pinter as "a good read, full of salt and pepper".