As reported on everythingtori.com:

“Unfortunately Tori has had to postpone her show tonight at London’s Savoy Theater due to illness.

Tori is hugely disappointed, this being the first time in her 20-year career that she has had to postpone a show due to illness.

The show will now take place on Monday, May 11, 2009. Tickets will remain valid for the new date and customers can check with their respective ticket outlets for more information. ”

And Twittered: 

“Savoy show postponed due to Tori illness. New date will be May 11, tickets will remain valid. Check with ticket outlets for more details.” (Thanks to Veronica for this info)