Here comes the bride -- again! Singer and activist Annie Lennox tied the knot with American physician and founder of an HIV charity Dr. Mitch Besser on Sept. 15 in England. People reports that the Eurythmics frontwoman and her groom exchanged vows in front of 150 guests on a private boat on the Thames River. Wearing white for her third wedding, Lennox -- who sported a vintage 1920s headpiece -- was attended by her two bridesmaids, daughters Lola and Tali. Guests included Oscar winner Colin Firth and American comedienne Ruby Wax. Lennox reportedly met Besser in 2009 through his HIV-research organization, mother2mother, for which she fundraises.