Calderwood left Brighton to team up with Steve Bruce and become Aston Villa’s new assistant manager last week.
And Sidwell admits that losing Calderwood is a blow to Brighton, as the players had a very good relationship with him.
“Col was a very popular figure at the football club,” Sidwell said, when asked about Calderwood’s move to Villa. “He was a great go between. I think it’s hit the gaffer hard, but life goes on. I’m sure somebody else will come in and do just as good as job as Colin has done.”
Calderwood and Chris Hughton have been a team for much of their managerial careers so far, but the former decided that it was time for a change.
He moves to Villa at a time when the Midlands club appear to be improving, under the guidance of Bruce.
Villa are yet to be beaten since Bruce took charge, and they have begun to edge closer to the play off places.
The Villans are still in 16th place in the Championship table, but they are only five points away from the top six.
Villa are next in action at the weekend when they take on Cardiff City, where Calderwood is set to join Bruce in the dugout at Villa Park for the first time.