Complex sentence: According to US charity records, Werritty was listed as the UK executive director with an address corresponding to Fox's former room at the House of Commons, No.341 in the MPs' block at Portcullis House, which served as the charity's official headquarters.
Split into simpler sentences: According to US charity records Werritty is listed as the UK executive director with an address corresponding to Fox's former room at the House of Commons. He operated the organisation from Fox's room, No.341 in the MPs'block at Portcullis House, and it served as the charity's official headquarters.