The charities whose leaders feature in the Trustee Leadership Top 100 are taken from the Civil Society Charity 100 Index. The Charity 100 Index tracks income trends in the largest charities going back to 1996 and is based on the largest 100 charities by income.

Updated on a quarterly basis  each charity’s total income is divided into five main streams – legacies, voluntary, grants and fees, investment and trading. Total income and each of the five streams are tracked year-on-year to reveal growth patterns for total income and for each individual stream, and also allow comparison between individual charities or groups of charities included in the data set. Constituents are selected based on the average income over the last three years’ received accounts, assuming an organisation meets the entry criteria outlined in the flowchart.

The income of members of the Charity 100 Index ranged from £38.6m to almost £500m as of April 2008, while the minimum amount required for membership of the Charity 250 Index was £9.5m.