Ridgewell, who can operate at centre-back as well as left-back, stressed his desire to leave St Andrew's in the summer amid interest from Premier League clubs.
Blues, however, turned down a transfer request from Ridgewell which came within 24 hours of the close of the summer window.
He has remained at the Championship club over the first half of this season, making a total of 17 starts and two substitute appearances in all competitions.
But the 27-year-old has always remained on Albion's radar and Roy Hodgson could well come back in with a second bid for his services.
Ridgewell joined Birmingham from city rivals Aston Villa in a £2million deal during the summer of 2007.