The bulk of the collection comprises papers relating to Sinclair's involvement in the Fraser Island Defenders Organisation (FIDO) and the campaign to stop sand mining on Fraser Island. The FIDO papers include corporate records; correspondence with supporters, politicians and the media; papers relating to legal cases; scrapbooks; newspaper clippings and subject files. The papers also relate to Sinclair's interest in a number of other conservation organisations including the Wildlife Preservation Society of Queensland, the Australian Conservation Foundation (ACF), the Wide Bay Burnett Conservation Council and the International Union for the Conservation of Nature and Natural Resources (IUCNNR). Other conservation projects represented in the papers are the National Conservation Strategy for Australia and the Working Group on Rainforest Conservation. There are also papers relating to Sinclair's employment in adult education and Technical and Further Education in Queensland, his involvement in defamation cases and a small quantity of personal papers.