Neil Danns has left Birmingham to join Crystal Palace for an initial fee of £600,000.
The 25-year-old has struggled to ever really establish himself at St Andrews since joining Birmingham in the summer of 2006 from Colchester.
Danns has signed a three-and-a-half-year contract at Selhurst Park, with the eventual fee set to rise to £850,000 based on add-ons.
Birmingham boss Alex McLeish feels he could not stand in the player's way given the lack of first team opportunities City could offer him.
McLeish said: "We would like to bring other players in and that's going to hold certain players back.
"Neil is a guy who, at this stage of his career, should be getting first-team football and we wish him all the best."