Byrne broke the deadlock in the 7th minute when shooting past opposing keeper Stephen O Brien from close range after latching on to a through ball from O Neill and this was slack marking by the Longford defence who were almost caught out again in the 12th minute.
Jason was left in the clear again, only to be denied by Town netminder O Brien who made a point-blank save, but superior Shels eventually stretched their advantage in the 25th minute with a wonderful strike from O Neill who planted the ball in the top corner of the net for his fifth goal in five games.
A tremendous surge forward by commanding centre-half Colin Hawkins created the opening that led to Gary s cracking effort from outside the box, although Longford were unlucky not to close the gap when Dessie Baker had a well struck shot superbly saved by Shels keeper Dean Delaney in the 33rd minute.
The introduction of Dave Mooney , who replaced the injured John Martin on the stroke of half-time, improved matters up front for the Town who should have scored in the 52nd minute when Dean Fitzgerald shot straight at Delaney from a few yards out when a goal seemed certain.
While that was a fortunate let-off for Shels, they were nearly always in control and nothing much happened from there until the finish as Longford crashed to their first home defeat since losing by the same 2-0 margin against Pat Fenlon s side on April 21st.
LONGFORD TOWN: O Brien; Kirby, O Connor, Dillon, Prunty; Martin, Fitzgerald, Byrne, Barrett; Baker, Myler.
Subs:- Mooney for Martin (inj, 45 mins); Cronin for Barrett (74 mins).
SHELBOURNE: Delaney; Heary, Hawkins, Rogers, Cahill; Ryan, Ndo, Crawford, Hoolahan; J. Byrne, O Neill.
Subs:- Crowe for O Neill (63 mins); S. Byrne for Crawford (63 mins); Fleming for Ryan (87 mins).