The three founders, Dr. William Robert Woodman, William Wynn Westcott, and Samuel Liddell MacGregor Mathers, were Freemasons and members of Societas Rosicruciana in Anglia (S.R.I.A.).
Dr. William Robert Woodman, William Wynn Westcott, and Samuel Liddell MacGregor Mathers, the founders of [something], were all Freemasons and members of the Societas Rosicruciana in Anglia (S.R.I.A.).