Nancy Forsyth was born Nancy Gray in Grantown-on-Spey and educated at Grantown Grammar School. She worked for the Post Office and Royal Bank of Scotland in Inverness, where her husband Willie Forsyth was a colleague. She became actively involved in politics after signing the Scottish Covenant in 1951, working first as a branch organiser for the Liberal Party in Inverness. She had joined and started to actively canvass for the Scottish National Party by the Pollok by-election in March 1967, later helping to establish the SNP's Black Isle branch with her husband and teaching the art of canvassing to other activists. She joined Wendy Wood's Scottish Patriots society during the early 1970s, and promised to accompany Wood on hunger strike for Home Rule over the threatened withdrawal of the Green Paper on the government of Scotland in 1972. She canvassed in support of Winnie Ewing in elections for the European Parliament, but remained staunchly Eurosceptic, having supported the anti-Common Market 'No' campaign during the 1975 Referendum.

Forsyth's main political tactic in pursuit of nationalist and other, including environmentalist and animal welfare, goals was to write to politicians, journalists, newspapers, and television channels and encourage others to do likewise until a response was forthcoming, activity for which she believed she was at times under investigation by the security services. She also engaged in smaller-scale actions including leafleting and encouraging the display of the Saltire flag on public buildings in Scotland. With her husband, she was also an active local fundraiser for the Church of Scotland.

The papers comprise Forsyth's incoming letters from MPs, civil servants, broadcasters, and organisations in response to her comments and questions on a range of political and constitutional subjects; papers relating to Forsyth's membership of the Scottish Patriots and friendship with Wendy Wood; and signed copies of books by nationalist authors, with a transcript of an oral history interview on Forsyth's political activism made by an unnamed researcher in 1993.