Lester struck in the 59th minute to cancel out Spencer Weir-Daley's 45th minute opener for the visitors who were on course for only their third away win of the season.
That would have flattered County who had been second-best for most of a first-half which Chesterfield dominated without making the most of their superiority.
Chances were created but not taken and it was an all too familiar scenario for the home side when they conceded a soft goal.
But by then they should have been well in control and surprisingly Lester had missed the sort of chance he normally tucks away while Peter Leven had also failed to cash in on another good opening.
The quality of Chesterfield's passing and movement had County chasing the game but Leven shot straight at Russell Hoult in the fourth minute and the midfielder also forced the experienced keeper into a sprawling save 12 minutes later.
Another chance was missed when Aaron Downes shot straight at Hoult and Mike Edwards cleared a Ward effort off the line before County stole the lead.
Neil MacKenzie played the ball in on the left and Weir-Daley punished some hesitancy from Downes before taking the ball around Barry Roche for only his third goal of the season.
He should have added another in the 48th minute but shot wildly over the bar after getting behind the home defence but Lester made no mistake when his next chance arrived.
Leven knocked the ball up to the striker who got around Michael Johnson to chest it down and place a shot past Hoult from eight yards.
Chesterfield could have won it after that but Lloyd Kerry rattled the crossbar from 20 yards and despite some late pressure the visitors hung on, giving 1200 of their supporters something to cheer at the end of what has been a miserable season for the club.