Indeed, Walder followed the lead of his Newcastle team-mate Jonny Wilkinson by booting a late drop-goal to secure a dramatic win.
With gusting winds and persistent rain, this was never going to be a high-scoring match. But the Falcons were determined to have a run and, in the early stages, the Northerners looked impervious to the greasy conditions.
Their adventurism paid of the sixth minute after a five-metre scrum saw the ball fed to Walder, who linked with inside centre Mark Mayerhofler and took the return pass before setting up unmarked outside centre Jamie Noon with a simple run-in.
After Walder had added the conversion, the Falcons kept up the pressure on their hosts and got the fly-half close enough to slot a good penalty.
The visitor's ambitious gameplan kept the Exiles pinned in their own half for the majority of the first 30 minutes, but fly-half Barry Everitt managed to keep his team in touch with two long-range penalty goals.
The Irish went into the break trailing 10-6, but Walder soon punished them for indiscipline by kicking another penalty.
Everitt replied with another penalty of his own before his halfback partner Darren Edwards failed to notice a two-man overlap that would have given them a try.
Everitt made up for the error by scoring a nice drop-goal, and – with just 12 minutes to play – it looked like the Falcon's away jinx would continue.
But the burly Newcastle forwards muscled their way up field and forced the home side to concede a penalty in the 79th minute.
Walder duly took the lead before immediately following up with a drop-goal to put the result beyond doubt.
Newcastle's win sees them leap-frog over Gloucester in the Zurich Premiership table, whilst The Exile's point for finishing within seven points sees them into fourth-place.
For London Irish:Pens: Everitt 4DG: Everitt
For Newcastle Falcons:Try: NoonCon: WalderPens: Walder 3DG: Walder