Three minutes into injury time Jason Jones magnificently turned a close-range header away for a corner.
There was more to follow in a frantic finale to the half with skipper Young doubling his side's tally in injury time.
In injury time Hitchin rued yet another missed chance as Lynn somehow kept out a goalmouth scramble.
With a goalless draw looking nailed on, United again hit the self-destruct button two minutes into injury time.
In the fifth minute of injury time Ireland won a scrum to the right of the English posts.
