Spireites succumbed to a goal in each half from Conor Washington.
The former Newport County striker headed in the key opener right at the end of a first half that had seen the visitors defend extremely well, his second came after some dreadful defending by Chesterfield.
The defeat was the team’s seventh in the league in a row, the worst since 1988 in a season of relegation and no goals have been scored in the last five of those defeats.
Chesterfield now sit just one place above the drop zone ahead of today’s game against high-flying Coventry City, a game that will see Danny Wilson making the decisions for the first time.
The new boss sat in the stands at London Road observing his new side’s performance and the game will have given him plenty to think about.
Posh created 26 shots to Spireites’ three, though the majority of the hosts’ efforts came in the second 45 after a much more even opening half that had seen Ollie Banks header on target and Sylvan Ebanks-Blake force a Ben Alnwick save from an angled effort.
Peterborough striker Souleymane Coulibaly had looked sharp in every department bar finishing.Lee twice denied him and he wasted two good chances, shooting wide, whilst Chris Forrester had hit the top of the bar with a cross and a well-deserved shut-out looked odds-on as the fourth official held up the extra minute board.
At that point the lively Jon Taylor passed to Marcus Maddison, who was gifted far too much space, and he delivered a fine ball onto Washington’s head to enable him to score his 12th goal of the season.
With the goals for column of Chesterfield not being troubled of late, that was a major blow.
Interim boss Mark Smith said: “We’d done alright in the first half without being spectacular, we rode our luck a few times and Tommy Lee made a couple of good saves; we had a couple of situations at their end and we just thought that if we could get into half time at 0-0 and then make the changes we were thinking about doing it would have been better than conceding in added time.
“In the situation we’re at, with not scoring, it’s like a double body blow.
“After that we had to make the changes anyway and for the first 20 minutes of the second half I thought we were quite competitive but the second goal killed us off.”
Those changes saw 18-year-old debutant Derek Daly, who started at left-back in a 4-1-4-1 but was switched to midfield in a 4-4-1-1, withdrawn, whilst Charlie Raglan reported an injury at the break so he had to drop out; Richard Wood and Lee Novak came on into a 4-4-2 line-up.
The game opened up but all the chances were falling to the hosts who saw Taylor run down the left and deliver a low ball that went through everyone and looked destined to go in at the far post.
However, the enthusiasm of Harry Beautyman got the better of him and he helped the ball over the line leading to an offside flag ruling out what was set to be a valid goal.
It hardly mattered as within seconds a second goal was scored legitimately. From the quick free-kick, Jay O’Shea gave the ball away, Chris Forrester delivered a pass to Washington, one of a number of Posh players in forward positions and he made no mistake with his shot to all but end the contest.
With a crisis of confidence needing to be addressed sooner rather than later, Smith said: “The appointment of Danny Wilson is a must for the club; when you’re doing a caretaker role, you’re not the full time manager and players will respond in a certain way.
“I’m not saying for one minute they’ve been against me because they’ve been brilliant. They’ve done everything I’ve asked of them, applied themselves properly, tried their best but you need someone that the players know is the manager. The Gaffer will come in now and hopefully work his magic and get us back up the table a little bit.”
With Raglan and possibly Dan Gardner added to the injury list, the one piece of good news for this afternoon’s game is the availability of Sam Morsy, back after a two game suspension. Chris Herd, back on the bench on Saturday, could also be brought back to add some steel to Spireites’ midfield.
Peterborough: Alnwick 6, Smith 7, Santos 7, Bostwick 7, Maddison 7, Taylor 8, Oztumer 6 (Samuelson 69, 7), Forrester 7, Beautyman 6 (Baldwin 80), Washington 8, Coulibaly 6 (Angol 69, 6). Subs: Henry, Fox, Addison, Nicholson.
Goals: Washington 45+1, 72
Chesterfield: Lee 7, O’Neil 7, Evatt 7, Raglan 5 (Wood HT, 6), Daly 5 (Novak HT, 5), Hird 7, Gardner 4 (Simons 66), Banks 4, Donohue 5, O’Shea 5, Ebanks-Blake 5. Subs: Cairns, Dieseruvwe, Ariyibi, Herd.
Referee: Andy Woolmer (Northants).
Booked: Banks (Chesterfield), Maddison (Peterborough).
Attendance: 7153 (526 from Chesterfield).