The core of the CHOGM are the executive sessions, which are the formal gatherings of the heads of government to do business. However, the majority of the important decisions are held not in the main meetings themselves, but at the informal 'retreats': introduced at the second CHOGM, in Ottawa, by Prime Minister of Canada Pierre Trudeau, but reminiscent of the excursions to Chequers or Dorneywood in the days of the Prime Ministers' Conferences. The rules are very strict: allowing the head of the delegation, his or her spouse, and one other person. The additional member can be of any capacity (personal, political, security, etc.), but he or she has only occasional and intermittent access to the head. It is usually at the retreat where, isolated from their advisers, the heads resolve the most intransigent issues: leading to the Gleneagles Agreement in 1977, the Lusaka Declaration in 1979, the Langkawi Declaration in 1989, the Millbrook Programme in 1995, the Aso Rock Declaration in 2003, and the Colombo Declaration on Sustainable, Inclusive and Equitable Development in 2013.