However, even with a second leg to come in Reading next Wednesday, it seems their bid might now be over after a costly final quarter at Headingley left them trailing by 11 points.
Bryan Redpath’s side, in their maiden Championship final and having finished second behind the leaders, were good value for a 15-13 interval lead in front of a crowd of 4,126, their biggest attendance since a play-off against Newcastle Falcons four years ago.
They had gained confidence with every minute that passed in that first period, scoring two tries, the second of which from Jonah Holmes in the 26th minute was arguably one of their best this season with the way it was created and executed.
But, having seen Irish respond, they will rue their failure to then capitalise when Brendan McKibbin, the Exiles scrum-half, was sin-binned for a panic moment, blocking Chris Elder as the full-back chased down his own kick in the 68th minute.
The Carnegie player may well have beaten Topsy Ojo in the race to the line – who knows? – but still they should have eaten into their opponents’ 20-15 lead with more than Joe Ford’s resultant penalty.
Instead, by the time McKibbin returned, the visitors were actually 26-18 ahead after expertly managing the game in Carnegie’s half, Tommy Bell slotting two penalties as their scrum took control and another in the penultimate minute.
Irish were fortunate, though, to still have 15 men on the field after Aseli Tikoirotuma felled Holmes with a swinging arm in the 42nd minute.
The Carnegie winger required lengthy treatment but recovered enough to prevent Ojo scoring in the corner soon after.
That, however, was mainly down to a woeful pass from James Marshall, Irish’s former New Zealand Sevens fly-half who, like many of his colleagues, initially lost his usual crispness under pressure.
The favourites were clearly unnerved at times, another instance being No8 Ofisa Treviranus fumbling at the back of an attacking scrum after being harried by scrum-half Alex Davies.
Holmes’ 14th try of the season was brilliant.
Fly-half Ford, playing with a genuine willingness to get his midfield moving, found recalled centre Tom Casson, whose well-timed short pass sent Pete Lucock surging into space.
The outside centre then showed real poise to deliver an accurate long pass to Holmes, the alert winger who similarly demonstrated a cool demeanour to get on the outside of Ojo and finish off from 30 metres out.
Ford converted to put the hosts in front and they were unlucky not to increase their lead further, Elder’s final pass to Holmes after another sharp move wide proving marginally forward. The visitors had gone 13-6 ahead when one of their own props, the enormous Danny Hobbs-Awoyemi, trundled through an alarming gap on Carnegie’s 22 in the 14th minute.
Bell converted having also fired over two penalties inside the opening eight minutes, punishing the hosts after they infringed following some poor exits from the kick-off and a restart. Nevertheless, Nick Kennedy’s side rarely offered much more threat to Carnegie’s line in that first period, limited to a chance when Alex Lewington made a brilliant weaving run from one 22 to the next, yet even then the winger lost possession when Holmes made the tackle.
Carnegie had responded well to Hobbs-Awoyemi’s effort, scoring their first try of the night within just three minutes.
A trademark Ryan Burrows’ busting carry earned them a penalty and, from the line-out, lock Ben West half broke before finding Mike Mayhew, the former Irish hooker, on his shoulder to finish off with some aplomb.
However, a reinvigorated Irish arrived for the second period far stronger and once they broke Carnegie’s resistance through Fergus Mulchrone’s converted try in the 56th minute, the favourites showed all of the professionalism that had seen them lose just once all season, even when they down to 14 men.
Yorkshire Carnegie: Elder; Holmes, Lucock, Casson (McColl 78), Stegmann; Ford, Davies (Green 58); Beech (Boyce 55), M Mayhew (Graham 74), Faletua (O’Donnell 19-Beech 72), Smith (Myerscough 53), West, Stedman (Beck 68), R Mayhew, Burrows.
London Irish: Bell; Lewington, Tikoirotuma, Mulchrone, Ojo; Marshall, McKibbin (Steele 65); Hobbs-Awoyemi (Court 58), Paice, Franks (Hoskins 76), de Chaves, Sinclair (Robson 52), Coman, Cowan, Treviranus (Narraway 65).
Referee: JP Doyle.