Calderwood was present to watch Blues' last-gasp 2-1 npower Championship victory over Burnley amid negotiations which would see him join the club's backroom staff and be reunited with manager Chris Hughton.
It comes after a summer in which Blues were thwarted in their efforts to prize Calderwood away from Hibernian, seeing a compensation offer in the region of £300,000 rebuffed by the Clydesdale Bank Premier League club.
However, his sacking at Easter Road on November 6 following just over a year in charge has paved the way to link back up with Hughton, although it is believed a severance package still needs to be agreed with Hibs.
The pair first worked together at Tottenham during Calderwood's playing days, before the former Scotland international was handed a coaching role at Newcastle in January 2009 alongside then Magpies assistant boss Hughton.
After twice taking the caretaker role at St James' Park Hughton was finally appointed permanent manager in October 2009, with Calderwood his assistant in the dugout as they guided Newcastle to the Championship title.
However, the duo parted ways after Calderwood accepted the top job at Hibernian in October 2010, with Hughton then relieved of his duties by Newcastle just two months later.
Hughton took the reins at Bkues over the summer and subsequently appointed Paul Trollope as first-team coach.
And despite being happy with his current coaching set-up he has always stressed he would be prepared to add an assistant to his ranks to further enhance his management team.
Blues are currently eighth in the Championship and well placed to progress into the knockout stages of the Europa League with two group matches remaining.