Nicholson was Founder Chairman and a Trustee of Earthwatch Europe which in 1989 launched interdisciplinary programmes to study the ecology of S'Albufera Natural Park, Mallorca, Spain, one of the largest wetlands in the Mediterranean basin. The project was intended to serve as a model for gathering and recording biodiversity survey data. Nicholson was heavily involved in the project from the start and University College London also participated. N. Riddiford and P. Newbould were among the principal scientific investigators. In 1993 an agreement was signed which shifted responsibility for the Park to the S'Albufera International Research Centre, though Earthwatch Europe and Nicholson maintained an active involvement in the welfare of S'Albufera.

Papers and correspondence, chiefly relating to the S'Albufera project. The bulk of the S'Albufera material was found packed into unmarked plastic wallets, the contents of which may fall within a narrow or wider date range. Papers were also found in inscribed envelopes or loose. This original arrangement has been maintained and a rough chronological sequence has been created.

A small group of papers at MSS. 15041/454-462 relates to Nicholson's other conservation interests in Mallorca. At MSS. 15041/463-465 is material relating to general Earthwatch Europe business only.

See MS. 15041/1655 for further correspondence relating to S'Albufera.