London Irish regained top spot in the Guinness Premiership after a ruthless display compounded Newcastle's relegation fears.

The Exiles climbed above Bath, who visit Leicester tomorrow, by destroying a Falcons outfit devoid of creativity, composure or confidence.

Irish had a try-scoring bonus point in the bag after just 30 minutes as wing Topsy Ojo, flankers Steffon Armitage and Declan Danaher and full-back Peter Hewat all breached Newcastle's defence.

With fly-half Shane Geraghty and number eight Chris Hala'Ufia running riot, the Falcons found themselves on a prolonged damage-limitation exercise.

They ultimately suffered the heaviest defeat by any club in the Premiership this season, remaining just one position above bottom side Bristol, a team they visit next month.

Prop Alex Corbisiero scored Irish's fifth try early in the second period, while Hewat kicked four conversions and a penalty before going off among a number of substitutions.

England World Cup winner Mike Catt, now a key member of the Irish coaching staff, also touched down, showing he can still handle Premiership business despite celebrating his 37th birthday almost four months ago.

Centre Seilala Mapusua made it a magnificent seven tries for Irish approaching full-time - Geraghty converted - and all Newcastle could manage was a breakaway consolation score for wing Tim Visser.

Irish showed two changes from the side beaten by Saracens last weekend, as Tom Homer replaced injured wing Sailosi Tagicakibau and England Under-20 prospect Corbisiero started instead of Clarke Dermody.

Newcastle, meanwhile, welcomed back their ex-All Blacks prop Carl Hayman following his recovery from a knee injury, and Rory Clegg wore the number 10 shirt vacated by Jonny Wilkinson since early October.

The Madejski Stadium's undersoil heating had been switched on since last Tuesday, removing any chance of Irish's first 2009 home game falling victim to the freezing conditions.

Newcastle, despite starting the match 21 points and nine places behind Irish, made a lively start and Falcons wing John Rudd was only denied a try by some last-ditch defending.

But Irish then struck with a 10-point blast in five minutes, leaving the Falcons floundering as they displayed a far sharper attacking edge.

Hewat kicked a penalty, and then added the conversion to Ojo's try after the England international intercepted Newcastle scrum-half James Grindal's wildly-optimistic pass near halfway.

Clegg opened Newcastle's account when he booted a 16th-minute penalty, yet the Exiles were up and running, already looking capable of posting an emphatic success.

England attack coach, the former Irish rugby director Brian Smith, looked on as Newcastle conceded three more tries during a devastating seven-minute spell when the Falcons defence was horribly exposed.

Armitage dived over unopposed from the back of a short-range lineout, then Danaher dashed through an inviting gap before Hewat collected Irish's inevitable bonus-point try.

Newcastle had no answer as Geraghty's incisive running freed centre Elvis Seveali'i, and the Samoan's exquisite inside pass was gathered by Hewat, whose subsequent conversion left the hapless Falcons 29-3 adrift.

Newcastle, without a Premiership away win since December 2007, were down and out by half-time.

Rugby director Steve Bates responded by making a double half-time substitution, sending on prop David Wilson and hooker Rob Vickers, but the only issue surrounding a hopelessly one-sided contest was how many points Irish would score.

And Irish quickly resumed normal service, smashing through the Newcastle defence for a fifth try, which was claimed by Corbisiero with Hewat's extras making it 36-3.

The game won, Irish boss Toby Booth could afford to ring the changes and Catt was given a run-out, replacing Hewat, with Geraghty switching to full-back.

Catt's arrival gave Newcastle even more to ponder, and they hardly helped themselves when substitute scrum-half Micky Young was sin-binned by French referee Christophe Berdos for a technical offence.

Catt then capitalised on shoddy Newcastle defence to collect try number six, before Visser's opportunist strike at last gave Newcastle's small band of supporters something to shout about.

Mapusua though had the last word by storming through another inviting hole in Newcastle's defence, with Geraghty's conversion making it a 40-point winning margin.