Bridges is out of contract at Elland Road at the end of the season and it had been widely reported that Sir Bobby would sign him then, but he has now arrived on what amounts to a trial basis.
The 25-year-old Geordie joined Leeds from a local Football League club in July 1999 and scored 21 times for the Whites during his first season, as they finished third in the Premiership and reached the semi-finals of the UEFA Cup.
Unfortunately a string of knee and ankle injuries have restricted him to just 26 Premiership outings in the last three-and-a-half seasons.
A talented striker, Bridges could prove to be a valuable asset to the club should he be able to remain injury free and recover his match sharpness.
Caldwell’s loan move to Leeds meanwhile is almost certain to have brought his Newcastle career to an end, as his contract expires in the summer and a renewal is unlikely, with The Daily Telegraph reporting that he has already agreed a deal to join the Mackems in the summer.
The 23-year-old centre-back has been at the club since leaving school and, although a committed player who worked hard to break into the line-up, never quite managed to establish himself as a first-team regular.
He leaves having made 18 starts and seven appearances as a replacement in the Premiership, scoring once - a cracker in the 2-0 win over Boro last season.