The defeat will sting the Titans Rotherham put they can take solace that they put in their best performance of the season and managed to a bonus point for ending within seven points of their victors. The point is the first of their season.
The win moves the Exiles into second place of the table thanks to tries at either end of the first half from Michael Horak and Paul Gustard.
In wet and windy conditions visiting fly-half Mark Mapletoft sent an early penalty kick wide of the posts, but made amends soon after by shimmied through the Titans' defence before sending a full-back Horak in for a try.
It seemed as though Horak's score would be the only one of a first half that was predictably punctuated with handling errors as both sides struggled to counter conditions that had put the game in doubt.
With the interval approaching replacement flanker Gustard skipped through a weak challenge on the Rotherham 22-metre line before running unimpeded under the posts. Mapletoft added the conversion.
The Titans lost back row man Brad McLeod-Henderson to be sin-binned for killing the ball once to often and the home side went into 15-0 down and heading for a another comprehensive defeat.
But – inspired by Ireland scrum-half Guy Easterby and centre Peter Jorgenson – the home side came into the second half with all guns blazing and actually won the period 10-0.
Fly-half Jon Benson slotted an early penalty to get the comeback going before his replacement Phil Jones intercepted on the half-way line late in the game to put Wood through from 40 metres out.
The wing slithered over in the corner and it needed a perfectly judged kick form Jones to finally break his club's Premiership points duck.
For Rotherham: Tries: WoodCons: JonesPens: Benson
For London IrishTries: Horak, Gustard Cons: Mapletoft Pens: Mapletoft