Not for the first time in this season of peaks and troughs Norwich City elected to do their talking on the pitch.

The Canaries' stock response to adversity is a tendency to circle the wagons and come out punching even harder. Few outside Norfolk would have given them an earthly of overcoming Arsenal following heavy top flight defeats to Liverpool and Chelsea. Fewer still could have predicted a club record unbeaten Premier League run which repaired much of that early season damage and extricated City from the developing fight for survival towards the lower reaches.

Then after a wretched festive spell notable for plenty of toil and spirited endeavour but a lack of the precision and defensive discipline that formed the hallmarks of their pre-Christmas revival, the prospect of an FA Cup third round trip to a resurgent Peterborough hardly carried much appeal for Chris Hughton's squad.

The Norwich boss elected to make eight changes from his starting line- up that lost at West Ham on New Year's Day. There was an inherent bravery in Hughton's approach, for all the sound logic regarding the need to let some of his fringe men off the leash and the desire to rest some of his cornerstones.

Hughton and those 5,000 supporters in attendance at London Road reaped the benefits in a cohesive performance that was as vibrant as it was comprehensive.

City looked collectively dead on their feet at Upton Park for large swathes of the previous league game, until Simeon Jackson and Elliott Bennett entered the fray to inject some much-needed energy into Norwich's labours in the East End. Both were given their chance from the start at Peterborough and were the catalyst for a more comfortable FA Cup passage than the respective form lines of these protagonists may have suggested.

Peterborough were poor. Minus key personnel, Darren Ferguson's youthful charges lacked invention and drive to carry more than a sporadic threat on Declan Rudd's goal. Norwich's back-up keeper was belatedly pressed into action two minutes before the end of normal time when he dropped on Michael Bostwick's stabbed close-range effort.

It was an unacceptably sparse return, and Ferguson deserved more credit than his under-performing players for issuing fulsome apologies to those suffering Posh fans in their biggest home crowd of the season.

The manager's post-match contrition was refreshing, if cold comfort, given the genuine mood of optimism prior to kick-off.

The Championship strugglers succumbed with embarrassing ease; lines were fluffed on a day in the footballing calendar now synonymous with minor tremors rather than the tectonic cup shocks of the past.

By accepting Peterborough's limitations, the danger is to dismiss the exemplary attitude and application of Hughton's revised line up at London Road.

Norwich started on the front foot and relentlessly exerted pressure with each passing minute camped inside United's half. Bennett's opener was remarkable only in the length of time it took for the Canaries to convert their territorial dominance and possession into tangible reward.

Bobby Olejnik had already acrobatically denied the midfielder-cum-striker after a slaloming surge and hit from outside the area. Olejnik was left exposed shortly after when Bennett cutely opened his body to touch Snodgrass' driven ball into a pocket of space between a posse of home defenders to guide a right-footer past the Austrian.

Snodgrass was again Norwich's most profitable supply line, but the Scot has delivered quality service and set piece sorcery against better opponents that Peterborough for the past month or so.

Bennett's misfortune, given his restricted opportunity to impress at Premier League level, is to seemingly compete with Snodgrass for that shift on the right of a three behind a lone frontman. Hughton's masterstroke at London Road was to harness both in the same starting roster.

City's formation on the day and the personnel who carried the club's colours into battle exuded a balance and a rhythm from front to back. Ryan Bennett and Leon Barnett remained largely untroubled. Marc Tierney and Simon Lappin combined in tandem.

David Fox and Bradley Johnson offered muscular intent and guile; the iron fist and the velvet glove in a midfield union that totally dominated three direct opponents in blue. Johnson was the wrecking ball in those key opening phases, Fox the pivot to switch play and bring the visitors' full-backs into the equation to expose copious acres of space down the flanks of Peterborough's suspect defensive three.

City's speed of thought and deed highlighted the divide between the Premier League and the rest.

Finance is only one disparity that separates the haves and the have nots as Peterborough's players appeared incapable of getting within range to deny Norwich the freedom to supply their creative threats at will.

The Canaries' second goal owed everything to Fox's vision and laser-guided precision, but Jackson's contribution should not be overlooked; the initial spin and run in behind was embellished by the chest control and lift over the stranded Olejnik.

The visitng celebrations were telling in the aftermath. Fox was embraced by as many of his team mates as the goalscorer for the sublime assist and skill few in Hughton's squad possess with such routine accuracy; and this from a man who only made his seasonal Premier League bow at West Ham as a late substitute just a few days earlier.

Hughton was right to emphasise the primacy of retaining the club's Premier League status ahead of the cup trip to their East Anglian neighbours; which is why a place in the fourth round – rubber-stamped by Snodgrass' 70th minute slot after Elliott Bennett had punished Shaun Brisley's misplaced ambition – may well offer only a short-term gain for the Canaries.

Of far greater importance was the shot in the arm ahead of Newcastle's Premier League visit this weekend and the knowledge Hughton does have genuine options at his disposal within his current ranks when top flight hostilities resume.

Fresh additions in the January window remain a priority for those inside the club and out, but the Norwich manager will have left London Road with plenty to ponder.

The more selection headaches he has, the better the Canaries' prospects of survival. That should be the enduring legacy of this FA Cup win.