The number of heads being shaken as a stunned Carrow Road emptied on Saturday attested to the fact that there was much that was hard to believe about what had just taken place. For a start there was how well Luton had played and in particular how well organised they had been. As their manager, Paul Buckle, with the slightly bemused air of one who still cannot quite believe how well the afternoon had panned out, said afterwards, the Conference side had come with a plan and, to a man, executed it to perfection.

It was not rocket science, said Scott Rendell, the much-travelled 26-year-old forward – Luton is his 13th club – whose goal 10 minutes from time secured the Hatters' place in the fifth round. Knowing the Norwich manager, Chris Hughton, would choose a similar line-up to that which brushed aside Peterborough of the Championship in the previous round, Luton set out denying them space, refused to be pulled out of their defensive shape and, when the opportunity arose, hit decisively on the counter.

"We couldn't afford to open the pitch up, it would have been suicide, so we cut it in half by letting them come on to us, we pressed well, limited them to two chances and, not only were we good enough to do that, but we were good enough to break and be clinical," said Buckle.

The winner was, indeed, a classic of its kind. Buckle, like Hughton, had brought on three substitutes and, while Stuart Fleetwood, JJ O'Donnell and Rendell may not be quite as well known as Grant Holt, Anthony Pilkington and Wes Hoolahan, it was the Luton trio who made the impact. Fleetwood's pass, curled with the outside of his foot into the left channel, sent O'Donnell scampering away before he looked up, checked and pulled the ball back for Rendell to get in front of his marker and poke the ball past the City goalkeeper, Declan Rudd.

But every man was a hero. Tyler, born in Norwich and on the club's books as a schoolboy, pulled off a fine save from Holt's diving header and, when Luton needed fortune to be on their side, it was, most notably when Leon Barnett's first-half header hit the post and appeared to have crossed the line before being cleared and in the final minute when Lathaniel Rowe-Turner inadvertently handled in his own penalty area.

That the result was deserved, however, was evident from the thousands of Norwich supporters who, to their huge credit, waited patiently to applaud the Luton players off the field. It took a while because the celebrations in front of the 4,000 travelling supporters were, understandably, emotional. "I'm so pleased for the fans, they've been right through the mill in the past few years and this and the win against Wolves in the last round will hopefully keep them going, following us up and down the country," said Buckle.

Jon Shaw, who ran himself into a state of exhaustion before being replaced by Rendell, admitted to being almost overcome. "I had a little wobble in front of the fans; I started to well up. But we didn't look like a Conference side against a Premier League side," he said. Nor did they. "We thought we could do well, but no one really expected this."

For Tyler, who after being let go by Norwich played almost 500 games for Peterborough before joining Luton in 2009, the hard part was the emotional side. "It's where I started. This is where I wanted to be as a little boy playing football," he said. "To come back here, play and keep a clean sheet means the absolute world to me and my family."

Lovely, heart-warming stuff this may be but for all that it is not just supporters of a certain generation to whom it will seem strange to see the result described as the biggest giantkilling for 24 years. Luton Town are not a Sutton United, whose victory over Coventry City in 1989 was the last time a non-league side knocked a top-tier side out of the competition, or an Altrincham, who beat Birmingham City away from home in 1986.

And while it might have been 1988 when Luton finished ninth in the First Division, reached the semi-finals of the FA Cup and won the League Cup, it was only six years ago that these clubs were playing each other in the Championship. Luton's decline since then, incorporating a further three relegations, as many periods in administration and a total of 40 points deducted for financial irregularities under a series of owners who should never have been allowed near a football club, reflects almost as badly on the game's authorities as on those who drove the club to the very edge of destruction.

Delighted though their supporters will be, then, what matters is regaining Football League status and Buckle is hoping plenty of the £90,000 reward for winning this game, not to mention the £250,000 made from the Cup run as a whole, will go towards strengthening his squad for the run-in. "We're half way through our league season, we're in the fifth round of the FA Cup and still in the FA Trophy. I can't ask any more of our players," he said.

"We've missed out on so many players of late, the one thing we have to do is add to the squad. It's money I'm sure isn't accounted for, and what we have to do is plan on how we're going to take the club forward. That's all I want to do."

Man of the match Mark Tyler (Luton)