The Blues had decent opportunities in the first period. A high ball in fed in Lorrell Smith but he was denied.
From an corner Smith broke clear but he was stopped by a good tackle that looked a foul but only a corner was given. From this Tom Guiney’s header was cleared off the line.
Irchester took a shock lead on 41 minutes as a long ball bounced and beat Ponting, falling into the path of Ryan Lovell and he made no mistake.
On 50 minutes Mukudzeyi Makuza sent in a deep cross that went over the full back but found Ash Fuller who made no mistake for 1-1.
The game lost intensity before the controversial moment; Lewis Sinclair made a sliding tackle, the ref thought he was high and uncontrolled and pulled out a red card.
In extra time Arlesey had a goal disallowed before, from a cross, Nathan Haycock headed in the winner.