Two goals in quick succession from Siriki Dembele in the first half and a last-gasp strike from top scorer Jonson Clarke-Harris sealed the Posh success and in truth they could have doubled their margin of victory with more composed and clinical finishing. Clarke-Harris even managed to miss a second half penalty.
Posh are now five points clear of Sunderland who have a game in hand, at Wigan on Tuesday night.
There was a surprise in the Posh starting line-up, not with Sammie Szmodics missing out with a shoulder problem, but with Mo Eisa’s inclusion. The club record signing was handed his first start since February 16 to partner Clarke-Harris up front.
Dembele was also recalled with Harrison Burrows dropping to the substitutes bench. On-loan goalkeeper Josef Burkic was granted a Posh debut in place of injury victim Christy Pym.
Swindon left veterans Brett Pitman and Paul Caddis on the bench and their actual selection led to some head-scratching among the home press corps. Former Posh midfielder Anthony Grant lined up as a centre-back.
If anything Posh seemed just as confused at the start as they sat off Swindon and watched them pop the ball about albeit with little threat.
But the game changed in six Dembele-inspired minutes.
On 17 minutes Dembele picked up the ball up outside the penalty area, wriggled inside, was tackled, got up again still in possession, laid the ball back to Eisa whose excellent first-time flick found Dembele all alone behind the defence. He went past home ‘keeper Lee Camp before slotting home.
And on 23 minutes Dembele was the fortunate recipient of a kind rebound off a defender, but the rest was magical. The wing wizard beat one man, dropped Grant on his backside before firing into the corner.
Swindon failed to learn their lesson. Twice more Dembele danced into the area, but one attempt to find Eisa was intercepted and a more successful pull back was muffed by Jack Taylor.
The home side enjoyed plenty of possession in the first-half without threatening Bursik.
There was one scare when Reece Brown was caught in possession in his own area by Scott Twine who prompty threw himself to the ground. An act of simulation according to former Peterborough & District Junior Alliance referee Josh Brown.
The half ended with Dan Butler and Clarke-Harris both forcing Camp to turn shots behind.
Bursik was forced to show his quality 10 minutes into the second-half when Twine took aim from 25 yards. The strike was true, but Bursik flung himself to his right to save well.
Posh continued to threaten on the break, but suffered from an attacking approach that bordered on the casual.
Eisa had a chance to score only his second league goal of the season after being played in on the edge of the box, his touch put him through on goal but Camp stayed big and blocked the effort.
Posh thought they had the chance to make amends moments later when they won a penalty in the 61st minute. Clarke-Harris was clearly fouled by Camp following Taylor’s through ball, but after a discussion with hat-trick seeking Dembele about who should take the spot-kick League One’s leading marksman shot weakly and wide.
Substitute Burrows saw a shot blocked after fine work from Nathan Thompson befpre Dembele should have completed his hat-trick 15 minutes from time. Ward played him through after collecting a headed flick from Clarke-Harris, but the shot was hit straight at Camp with Burrows waiting for a tap-in.
Ward was next to miss after Clarke-Harris laid the ball into his path, but Camp again made the save.
Swindon’s veteran substitute Brett Pitman cleared the crossbar with two half chances in added time before Posh finally found that third goal in the last minute.
Substitutes Idris Kanu and Ricky-Jade Jones had slight involvements before Clarke-Harris slammed the ball home from 20 yards.
It was a margin of victory that flattered Swindon even though Posh were far from their best.
Posh: Josef Bursik, Nathan Thompson, Dan Butler, Mark Beevers, Frankie Kent, Joe Ward, Reece Brown (sub Ethan Hamilton, 75 mins), Jack Taylor, Siriki Dembele (sub Ricky-Jade Jones, 90 mins), Mo Eisa (sub Harrison Burrows, 68 mins, sub Idris Kanu, 90 mins), Jonson Clarke-Harris.
Unused substitutes: Dan Gyollai, Niall Mason, Louis Reed.
Swindon: Lee Camp, Jonathon Grounds, Taylor Curran, Anthony Grant, Dominic Thompson (sub Tom Broadbent, 63 mins), Jordan Garrick, Christopher Missilou (sub Joel Grant, 82 mins), Scott Twine, Jack Payne (sub Brett Pitman, mins), Matty Palmer, Hallam Hope.
Unused substitutes: Archie Matthews, Paul Caddis, Tyler Smith, Tyrese Omotoye.
Goals: Posh - Dembele (17 mins & 23 mins), Clarke-Harris (90 + 4 mins).
Cautions: Posh - Taylor (foul).
Swindon - Twine (simulation), Camp (foul).
Referee: Josh Smith 8