Correspondence and papers regarding the Isaac Newton Telescope Users Group, comprising a circular letter from E.M. Burbidge to interested parties asking if an informal group would be of interest to them; replies to Mrs Burbidge, most of which are in favour of her suggestion; agenda and invitations to the meetings of 24 January 1973, 3 October 1973 and 6 November 1974; reports of meetings of the informal group; a list of Isaac Newton Telescope users; and copies of domestic instructions to users staying at Herstmonceux Castle.