Dame Judi won the awards for best actress in a musical, in A Little Night Music and best actress, for Absolute Hell, both at the Royal National Theatre.
Dame Judi is still starring in the Stephen Sondheim musical and revealed she plans to stay with the show until August. She said: "I'd go on until I was in a Zimmer frame. I love it."
Dame Judi has already won the best actress award for Macbeth (1977), Juno and the Paycock (1980), Pack of Lies (1983) and Antony and Cleopatra (1987). But she said last night that she had lost half of these at a fire at her house two years ago.
Other winners last night at the London Theatre awards were Sam Mendes - tipped to become the next director of the Royal National Theatre - who was named best director for Company and The Glass Menagerie, both at the Donmar Warehouse, Covent Garden.
The best actor was Alex Jennings, for Peer Gynt at the Young Vic, and the best play was David Hare's Skylight.
Adrian Lester won the best actor in a musical award for his role as Bobby in Company, but the best musical itself was awarded to Jolson the Musical at the Victoria Palace. Jez Butterworth's Mojo was the best new comedy.
The Royal Opera House's production of Billy Budd won the best new opera category.
Playwright Harold Pinter won a special award for his outstanding contribution to theatre.Reuse content