OBJECTIVE: The death of former British Prime Minister Margaret Thatcher has offered many opportunities to reappraise her career. However it is not widely known that she acted as a consultant for the tobacco industry following her resignation from office. The availability of evidence from tobacco documents archives offers the opportunity to explore her work for Philip Morris, and more generally to assess how industry seeks to influence and use elected and former public officials. STUDY DESIGN AND METHODS: Analysis of documents from the Legacy Tobacco Documents Library (http://legacy.library.ucsf.edu). Memos, letters and other documents were sought which mentioned Margaret Thatcher or other key individuals. Documents (n = 151) were downloaded as PDFs. Of these 51 provided relevant information. RESULTS: Margaret Thatcher advised Philip Morris on issues including advertising bans, lowering of tobacco tariffs in EEC countries, reducing tobacco taxes, and anti-tobacco programs. She had previously been involved in moving two of her ministers from their posts in response to tobacco industry pressure. She advised Philip Morris to exert political pressure through the House of Commons by lobbying MPs against the Conservative government accepting ECOFIN, an European Union (EU) tax harmonisation agreement. Other activities included trips to Prague, Tokyo, Chicago, Geneva and Hong Kong on Philip Morris' behalf, or for meetings with Philip Morris executives. CONCLUSIONS: Relationships between politicians and industry remain relevant today, not least because Article 5.3 of the WHO Framework Convention on Tobacco Control includes the protection of public health policies from tobacco industry interference. The findings are consistent with findings from other studies which show tobacco industry attempts to influence governments, for example to attempt to weaken the WHO Framework Convention on Tobacco Control. They particularly point out the value of former senior politicians to industry, specifically their 'insider knowledge' which can be employed to gain access to and influence other policymakers on industry's behalf.