APGHG administrator Mark Glover said: "As a former government minister, his appointment is a big plus for the group."
The Landscape Institute is a new sponsor alongside HW, the HTA, BALI and Scotts, and subscriber The Royal Parks. The Corporation of London has dropped out after five years as a sponsor.
The group's annual reception will be on 24 November. Group members will visit either the Scilly Isles or Alnwick Garden in September and are likely to visit Chiswick Park and the gardens at 10 and 11 Downing Street.
A Landscape Institute visit, meetings with Defra secretary of state Hilary Benn and an HTA Greening the UK event at Parliament are also on the agenda for 2008.