Having been forced to retire from Saturday’s three-lap encounter when leading, the Nottinghamshire brothers made no mistakes this time around and took a 17.3s victory from Dave Molyneux/Patrick Farrance with Conrad Harrison/Mike Aylott having to settle for third on this occasion.
The Birchalls signalled their intentions from the start moving into a two-second lead at Glen Helen on the opening lap, with first race winners Tim Reeves/Dan Sayle slotting into second and Harrison a further one and half seconds back in third. Molyneux lay in fourth from John Holden/Andy Winkle and Gary Bryan/Jamie Winn.
There was no change at the top of the order over the remainder of the lap and a lap of 114.490mph gave the Birchalls a 10.7s lead over Reeves/Sayle with Molyneux/Farrance now moving up to third. Harrison/Aylott slipped back to fourth with Holden/Winkle and Bryan/Winn still in fifth and sixth.
Circulating ahead of Reeves/Sayle on the roads, the Birchalls extended their lead to 11.5s at Glen Helen on the second lap and that soon increased when the first race winners were forced to retire at Ballaugh. That promoted Molyneux/Farrance and Harrison/Aylott up into the podium places with Holden up to fourth and Dougie Wright/Martin Hull now getting the better of Bryan/Winn for fifth.
The Birchalls second lap was their personal best at 114.662 and although Molyneux/Farrance also lapped in excess of 114mph, they were now 16s behind. However, they were a similar distance clear of Harrison/Aylott with the top six remaining the same.
On the final lap, the Birchalls were able to maintain their advantage over Molyneux/Farrance and they took a superb victory thus following in the footsteps of Reeves in adding a TT victory to their World Championship success of 2009.
Harrison/Aylott took their fifth TT podium together with Holden/Winkle comfortable in fourth. Wright/Hull retired at Kirk Michael on the final lap and so Bryan/Winn took fifth with Gary/Dan Knight wrapping up their excellent TT campaign with sixth. Frank Lelias/Charlie Richardson did likewise in seventh with Wayne Lockey/Luke Capewell in eighth ahead of Dean Banks/Ken Edwards and Mick Donovan/Aaron Galligan, all of them achieving their best TT results.