The Cobblers slumped back to the bottom of the Football League with a terrible home defeat at the hands of a rampant Wycombe Wanderers.
Less than half an hour after a rampaging 4-1 win for Wanderers, Boothroyd was summoned to a board meeting, wherein it was decided he would leave the club.
His final game in charge of Northampton got off to the worst possible start as Wycombe scored in the first minute of the game through Jo Kuffour and doubled their lead through Kortney Hause.
Izale McLeod gave the Cobblers a second-half lifeline but further goals from Stuart Lewis and Dean Morgan ensured Wanderers came away with a deserved 4-1 win and all three points.
Torquay’s win at Dagenham & Redbridge mean Northampton will spend Christmas Day rooted to the bottom of Sky Bet League Two.
Just 14 seconds had been played when Kuffour struck, rattling home left-footed after a strong run down the right by Nick Arnold.
Matt Bloomfield then forced a good low save from Matt Duke before attempting another from long range that was closed down by Stuart Dallas.
They had the ball in the back of the net on eight minutes when Dean Morgan glanced in a cross only to see the effort ruled out for what looked a marginal offside.
The lead was doubled, with a certain grim inevitability, when a corner was returned to the taker, Max Kretschmar, by way of a mishit Bloomfield shot, and his ball in was eventually headed over the line by Hause.
Duke had to be at his best to prevent a third just three minutes later, rushing off his line to deny Kuffour with the ball spinning narrowly past the back post and away for a corner.
A rare double first-half substitution followed, With Ishmel Demontagnac and Roy O’Donovan brought on for Ian Morris and Clive Platt, both of whom were injured.
The best play came through Hackett, who played in Izale McLeod for Northampton’s first good chance with the match half-an-hour old.
The on-loan MK Dons striker rifled a shot straight at goalkeeper Matt Ingram, with Stuart Dallas, who by this point was playing central-midfield, failing to reach the rebound.
McLeod then skied when it looked easier to score after O’Donovan had seen his near-post effort blocked.
Boothroyd played it bold with his half-time substitution, putting on a striker - Luke Norris - for a centre-back - Paul Reid - and it paid off five minutes into the half.
A floated Hackett cross was marginally behind Norris but he got enough on it to nod into the path of McLeod, who stabbed home from eight yards.
Town were in the ascendancy when, with 22 minutes to go, their recovery suffered a setback.
In stretching to cover at the back, Mathias Doumbe suffered an injury and, with all three substitutes on, the home side were reduced to 10 men.
It killed Northampton’s growing momentum and, more importantly, mean a makeshift back four was in place for the game’s final quarter.
As they had done regularly in the first half, Wycombe punctured it with 10 to go, Lewis timing his run to perfect to thrash a shot past Duke.
Any semblance of confidence was shot by the time Morgan added a fourth, seemingly having all the time in the world to pick a spot inside the far post and round off a miserable afternoon for the Cobblers.
Within an hour of the match itself finishing, things got even more miserable for Boothroyd, who finds himself unemployed four days before Christmas.
Cobblers: Duke, Amankwaah, Reid, Doumbe, Widdowson, Hackett, Ravenhill, Morris, Dallas, McLeod, Platt
Subs: Demontagnac (for Morris 23), O’Donovan (for Platt 26), Norris (for Reid 46)
Not used: McNamara, Collins, Deegan, Emerton
Wycombe: Ingram, McCoy, Stewart, Hause, Wood, Arnold, Lewis, Bloomfield, Kretzschmar, Kuffour, Morgan
Subs: Knott (for Kretzschmar 72), McClure (for Kuffour 90+2)
Not used: Spring, Horlock, Cann-Svard, Morias, Angol, McClure
Away fans: 439
Referee: Simon Hooper