Beyond the minimum legal requirements, the governing documents of the charity will define who can be a trustee. Usually the only preclusions are disqualifications under the Charities Act (e.g. disqualified company directors, undischarged bankrupts or anyone removed as a trustee because of misconduct or mismanagement), not meeting the “fit and proper persons” condition, and failing any Disclosure and Barring Service (DBS) checks. The Charity Commission provide further detailed information relating to UK trustee roles in their guide: The Essential Trustee - what you need to know, what you need to do.
Each charity board will also require specific skills and experience that can help it achieve its aims (general management, finance, fund-raising, strategy, real estate, HR, digital marketing, regulatory, risk etc.). This is more important than ever as charities no longer settle for people they happen to know because they have become more aware of the value of a diverse boardroom. As a result, now is a good time to apply for a trustee role as many leading charities are looking to hire trustees for their boards.