Under the guidance of caretaker boss Guy Branston, the Spireites put up a terrific fight against the high-flying Hatters, but ultimately it wasn’t enough as the visitors slumped to another league defeat.
Branston just made a couple of changes to the Spireites’ line-up ahead of the game at Kenilworth Road.
In the wake of the previous week’s home defeat by Accrington Stanley, Matt Briggs was given the nod in place of Bradley Barry, while up top veteran Chris O’Grady slotted in to replace Kristian Dennis.
The Spireites made an encouraging start to life without Caldwell.
There was a confident air about the team in the early stages and O’Grady went close when he just failed to direct a firm header on target.
Back came the Hatters, with Danny Hylton heading narrowly over and Luke Gambin firing a shot inches past the post.
The hosts had the ball in the back of the Chesterfield net in the 15th minute, but James Collins’ effort was ruled out as the ball had strayed out of play during the build-up.
The Spireites fluffed a terrific chance midway through the first period. Sam Hird pounced on a loose ball inside the Hatters’ box, only to somehow scoop a shot over the top from close range.
The visitors kept the pressure on, and Matt Briggs was unlucky when his well-struck shot was saved by Marek Stech.
Andy Kellett was then guilty of a glaring miss just before the break, firing meekly at Stech from a great position.
The Hatters opened the second period with renewed impetus. Spireites ‘keeper Joe Anyon was soon called into action to keep out a firm strike from Pelly-Ruddock Mpanzu.
The hosts took the lead in the 53rd minute.
Mpanzu played in the dangerous Hylton, and he slotted impressively past Anyon.
The Spireites almost produced an instant response, but Louis Reed’s diving header was inches off target.
O’Grady was then inches away from meeting a low cross into the six-yard box from Briggs.
The Hatters soon grabbed back the initiative, however, and Hylton fired wide with 20 minutes left when a second goal looked on the cards.
The hosts were reduced to ten with 14 minutes left when Mpanzu was shown a straight red card following an ugly lunge on Kellett.
Late on Harry Cornick should have made it 2-0 to Luton, but he fired wide when it looked easier to score.