Rangers' leading scorer latched on to Tony Thorpe's through ball and coolly slotted home to earn Rangers a point that looked beyond them as the clock ticked down.
Peterborough were devastated having stifled Rangers for long periods and a somewhat disjointed display from the home team had looked likely to send the Loftus Road faithful home with nothing - until Super Kev's strike at the death.
The Rangers manager had been forced to make two late changes to his starting line up, after Martin Rowlands and Chris Day failed late fitness tests.
Matthew Rose was handed a start on the right of midfield, whilst Nick Culkin stepped up to replace the injured Day. Kevin McLeod also returned to the left flank, after falling ill just prior to kick off last Saturday.
Peterborough created the first chance of the game, when Clive Platt got the better of Gino Padula.
He sent in a low cross that was met by Andy Clarke in the box and although Posh’s top goalscorer connected with his first time volley, Nick Culkin held the shot.
Rangers then sprang into attack. Padula sent in a teasing cross which was met by the head of Paul Furlong, but was seen away for a corner by the rising Posh defence.
Rangers continued to apply the pressure, with Terrell Forbes sending in a powerful drive which kept rising over Mark Tyler’s crossbar.
The home side then forced a corner in the 10th minute - Marc Bircham playing in Gallen who was closed down before he could get a strike away.
Padula then sent his cross to the far post, which Furlong headed goalward. However, Furlong’s powerful effort was cleared awkwardly off the goal-line by Posh defender Sagi Burton – with appeals for hand ball waved away.
On 20 minutes Bircham made a piercing run through the heart of midfield. With the Posh defence backing off, Bircham took the ball inside the box, only to be felled while preparing to release his strike.
The Posh defender took the man rather than the ball, but again - play was allowed to continue
Gareth Jelleyman was forced out mid-way through the first half. Peterborough manager Barry Fry brought on Tommy Williams, who was welcomed back to Loftus Road with a mixture of boos and polite applause.
With only five minutes of the half remaining, Bircham won Rangers a free-kick 25 yards out from goal. Furlong and McLeod stood menacingly over the ball, with Furlong hitting his strike low after Palmer laid off the ball.
The ball ricocheted off legs and out wide to the right flank, with Rose forcing a corner from the follow up.
However, Peterborough were soon to take the lead, scoring in the 44th minute, and somewhat against the run of play. Williams sent in a delicious cross from deep on the left flank and Clive Platt rose unchallenged to head home from six yards out.
Posh had the first opportunity of the half, going close to doubling their lead. Curtis Woodhouse sent in a well weighted free-kick from the right flank, which found the feet of Peterborough’s Mark Alber, who should have done better, turning his first time shot around Culkin’s upright, much to the relief of the Rangers fans.
However, Rangers were intent of making inroads of their own. McLeod connected sweetly to a raking Marc Bircham ball which picked him out from 40 yards. However, McLeod saw his shot tipped over by Tyler in the Posh goal.
From the resulting Padula corner, Gallen volleyed from the clearance. His 25 yard shot sailed over a maze of bodies, but into the chest of Tyler.
A foul on Marc Bircham by Woodhouse then earned the Posh midfielder the first caution of the game on 52 minutes.
Seven minutes later, Ian Holloway rang the changes with no fewer than three substitutions.
Tony Thorpe came in attack to replace Furlong, while Richard Johnson came on for Palmer in the centre of midfield to make his first appearance in a Rangers shirt. Matthew Rose made way for Jamie Cureton.
However, only a minute later, Clarke Carlisle went down after colliding with Terrell Forbes. The Rangers defender was forced to leave the field, and the Rs continued with 10 men until Carlisle returned seven minutes later.
The injured Carlisle pushed up into attack, with Rangers throwing everything they could at the Posh defence. Bircham won another free-kick on 70 minutes, but Padula, this time, was too long on the cross.
Andy Clarke then made way for David Farrell as the Posh tried to firm things up - but it was Rangers who were on all-out attack.
First Gallen sent his shot sailing over the bar from close range on 75 minutes after latching onto a failed clearance. Then Cureton put through Thorpe two minutes later but the Posh ‘keeper beat him to the ball.
Rangers continued to press, but Peterborough went close again to catching Rangers on the break. Goalscorer Platt bored down on goal, forcing Culkin to come off his line.
Culkin, well out of his box, met the rising ball, colliding with Platt, but clearing the danger, and earning a caution for his troubles.
With four minutes of time added, Rangers continued to search for an equaliser. And it came, created by the initial touch from make-shift forward Carlisle, who found Thorpe running through on goal, slipping it to Gallen – who found the back of the net.
Rangers weren't satisfied and wanted more than a point for their troubles, but in the end it wasn’t to be, and they were forced to settle for a draw.
Rangers: Culkin, Forbes, Padula, Carlisle, Gnohere, Rose (Cureton, 59), Bircham, Palmer (Johnson, 59), McLeod, Gallen, Furlong (Thorpe, 59)
unused subs: Sabin, Marney
Bookings: Culkin
Sent off: -
Scorers: Gallen 90
Peterborough: Tyler, Legg, Arber, Newton, Woodhouse, Jelleyman (Williams 26), Burton, Thomson, Jenkins, Clarke (Farrell 74), Platt
subs: Kanu, Logan, Willock
Bookings: Woodhouse
Sent off: -
Scorer: Platt
Referee: Mr Armstron