The first half sending off of Luke Ruddick set Dunstable Town on the way to another heavy home defeat on Saturday afternoon.
The Blues had been leading 3-2 when Ruddick was dismissed for a second bookable offence after just 30 minutes.
The visiting Magpies demonstrated expertly how to maximise their numerical advantage and turned the screw in the second half to win comfortably.
Coming on the back of a six goal loss at Creasey Park last week the Blues have now conceded 11 goals in two games and will surely be pleased to have two league games on the road to rediscover their form.
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Dorchester’s arrival was delayed owing to motorway congestion and they got off to the worst possible start as the hosts scored on their first proper attack.
Alan Walker–Harris parried Adam Watkins’ shot but the ball fell for Elliot Bailey to finish with a tap in.
However after a quarter of an hour a Dorchester counter attack ended with Ben Watson perfectly placed to put his shot beyond Dunstable’s debutant goalkeeper Charlie May, former keeper Luke Chambers having had his contract cancelled.
Dunstable, who have also seen influential skipper Ben Herd depart for Boreham Wood, were back in front midway through the half.
Jemale McKenzie-Lowe scored two goals within a minute of one another - the first finishing after excellent work by Chris Marsh, the second set up by Watkins.
Dorchester were thrown a lifeline on on the half hour when Ruddick conceded a penalty which earned him his first yellow card.
May made a heroic penalty save and also stopped the follow-up shot, however his luck ran out when Jake Smeeton’s shot was deflected past him.
This first half packed in plenty of goals and incidents and the most significant were the circumstances that led to Ruddick’s two yellow cards.
The second was for a foul soon after that even the most lenient of referees could not have overlooked as the stylish, strong defender left a gaping hole in the already fragile home defence.
Ten man Dunstable still held the advantage going into the second half but rarely looked like troubling the Dorchester goal.
The hosts were unable to prevent three second half goals – with the first of these coming from a passing move that would rank with any fully professional team, finish by Sam Lanahan.
Chris Dillon gave the Magpies the lead for the first time with 15 minutes left to go and within two minutes full-back Bradley Tarbuck made it 5-3.
Dunstable Town now head to Frome Town tonight (Wednesday) looking to address their recent poor run, and follow that with a trip to Banbury United on Saturday.