|London Welsh (7) 12|
|Tries: Tincknell, Vea Con: Robinson|
|London Irish (38) 50|
|Tries: Lewington 3, Fowlie, Geraghty 2, Parr, Fenby Cons: Geraghty 4, Noakes|
Alex Lewington scored a hat-trick as London Irish eased to Premiership victory over winless London Welsh.
The visitors earned a bonus point within 30 minutes as Lewington and Tom Fowlie went over before Shane Geraghty crossed twice.
Matt Parr and Andrew Fenby also scored for Irish, who led 38-7 at half-time, Jason Tincknell replying for the hosts.
Lewington added his second after the restart before completing his hat-trick after Taione Vea scored for Welsh.
Irish's victory - their biggest in the Premiership this season - lifts them above Newcastle to 10th in the table, while the home side still only have one bonus point to their name.
Welsh, who had lost all 25 games this season prior to the visit of Irish, made six changes from the side that were beaten at Gloucester.
But it made little difference to their fortunes as wing Lewington went over in the corner before Fowlie won a foot race to touch down after a loose Welsh pass had been hacked on twice by the visitors.
Tincknell capitalised on a Opeti Fonua break to score for Welsh, with Will Robinson's conversion closing the gap to 10-7.
But that would be as close as Welsh would get as Geraghty darted through a gap in the line to score under the posts before pouncing on an overthrown lineout to grab his second.
Parr scored his first try of the season from a catch and drive, before Fenby completed the first-half try-scoring after good work by Lewington.
Tom Guest offloaded for Lewington to sprint clear early in the second half, but, after Irish had Fenby yellow carded for infringing near his own line, Welsh made their extra man count when Vea powered over.
But it was Lewington who had the final say, side-stepping his way through in the final seconds to complete his treble.
London Welsh assistant coach Ollie Smith: "Shane Geraghty ran the show, he's an outstanding player and he is very astute and I only wish we had him in our ranks.
"We didn't look after the ball and when we gave the ball away it was catastrophic but we didn't look after it well enough.
"It's been a disastrous season and we've not achieved what we wanted but we are not giving up."
London Irish coach Glenn Delaney: "We were determined to give them a lot of respect and in the first half we were very clinical and really sharp. We scored tries from all aspects of our game which was very pleasing.
"We decided to take some of key players off at half-time as we want a depth in our squad and it's important that certain players have game time.
"We wanted to treat the second half like a new game with some different players but it did become very fragmented."
London Welsh: Kear; Stegmann, J Lewis, Tincknell, Scott; Robinson, R Lewis; Aholelei, Elloway, Gilding, Schofield, Corker (capt), Pienaar, Kirwan, Fonua.
Replacements: Morris, Trevett, Vea, Down, Thorpe, Davies, Barkley, Reynolds.
London Irish: Fenby; Lewington, Fowlie, Sheridan, Short; Geraghty, Steele; Parr, Paice, Halavatau, Skivington (capt), Rouse, Treviranus, Gilsenan, Guest.
Replacements: Stevens, Court, Palframan, Sinclair, Narraway, Allinson, Noakes, Griffin.
Sin-bin: Fenby (50)
Referee: Matthew Carley (RFU)