After Robin Lod curled an effort off the post, and then Oliver Antman’s low strike was touched onto the woodwork off the studs of defender Nathan Collins, the first decisive moment in Dublin came when Ferguson rose highest to head home the opener.
It came after some superb work by Mikey Johnston down the left, and the winger’s dinked cross was met by Brighton striker Ferguson, whose face was a tale of relief as he grabbed his first international goal in more than a year after an injury-hit few months.
“It was a lovely goal,” Hallgrimsson added.
“Especially in the first half I thought we hurt them on the wings. We moved the ball quickly and got in a one verses one position. Both Mikey and Festy [Ebosele] did a brilliant job.
“We should have moved the ball more side-to-side to use more of the advantage that we had.”
While the Kelleher save from Pohjanpalo was crucial in securing the win, Hallgrimsson was delighted with his team’s “fight” across the pitch.
“The energy was there, the enthusiasm was there and the fight was there.
“We were winning duels. That is all factors that will help you win matches.”
As for England, who won 2-0 in Dublin in September’s Nations League opener, Hallgrimsson knows the challenge that awaits.
Despite a depleted squad which saw nine players withdraw ahead of Thursday’s game in Greece, England ran out 3-0 winners but still need victory over the Irish in their final match to secure top spot in League B2.
“They will need a win to win the group,” Hallgrimsson said with a smile.
“We’ll give our best in that one.”