The tone had been set by the Tannoy man before kick-off. "Have Chelsea got the fight for it," he asked as the teams took the field. "Have they got the bottle?" In the end Claudio Ranieri's side showed just enough of those qualities but it was nerve-janglingly tight.
Three goals ahead after 25 minutes, Chelsea tottered in typical away fashion to inject drama into a tie that had been heading for anti-climax. Not until Eidur Gudjohnsen scored their fourth deep into injury-time was Gillingham's stirring recovery killed off.
The First Division team deserved their ovation at the finish but it Chelsea who can look forward to a fifth-round tie at Arsenal. Their wait of almost 10 months for an away win is over but the stern look on Ranieri's face proved that relief rather than celebration was the overriding emotion.
"I have heard a lot about the FA Cup and everything I have heard was true," reflected Jesper Gronkjaer, scorer of two goals on an impressive first start for Chelsea. "It was very difficult. You saw what happened in the second half.
"I have played in many stadiums in front of many people but this crowd was amazing. I have a lot of respect for them. You have it in the back of your mind that maybe they will get it to 3-3 and then it would be difficult."
Such a close finish had seemed impossible at half-time. The pace and movement of Chelsea's attacks had been too much for Gillingham.
Those who wondered whether Chelsea had thrown away £7.8m on Gronkjaer after the long, injury-laden wait that followed his move from Ajax were treated to a fine performance as the 23-year-old flitted from flank to flank and scored twice.
With Eidur Gudjohnsen bustling menacingly around him, the holders looked in little danger. If there was no doubting Gillingham's fight, it seemed they had lost their bottle on the big occasion.
Yet led by their indefatigable captain Paul Smith, and helped by the introduction of the muscular Iffy Onuora at the interval, they produced a memorable fightback. First Paul Shaw and then Onuora pounced, and for the last 25 minutes Chelsea held out nervously as the decibel levels rose among an excited crowd.
"We believed perhaps we could nick another but it wasn't to be," said Gillingham's player-manager Andy Hessenthaler. "We made it hard for ourselves with our performance in the first half. You could see the difference in the leagues then and their class but we're disappointed with the way we defended."
Chelsea's pleasure at progressing will have been tempered by the sight of Jody Morris departing on a stretcher with ankle ligament damage, the full extent of which should be known today after a scan.
Frank Leboeuf, too, was carried off with a dead leg. His future, as well as his fitness, is in doubt after the Monaco president Jean-Louis Campora said he had no intention of signing the 33-year-old. Other reports last night suggested Monaco were simply looking to find the fee of around £2.5m.
Leboeuf had played a role in Chelsea's opener, his long ball culminating in Barry Ashby misdirecting a header back to Vince Bartram, which allowed Gudjohnsen to nod the ball into an empty net.
When Gronkjaer scored twice in 10 minutes after a spell of Gillingham pressure, first running on to Gudjohnsen's pass and cutting in to score with his right foot and then latching on to a Gianfranco Zola pass that caught out Chris Hope and scoring with his left, it seemed game over. But nothing is straightforward on Chelsea's travels. Shaw slid in the loose ball after Onuora's run had been stopped and 15 minutes later Onuora headed in after Carlo Cudicini had parried Nicky Southall's free-kick to give Gillingham hope.
But the chance they craved never arrived and Chelsea, who hit the post and bar in the second half, could finally relax when Gudjohnsen volleyed in Graeme le Saux's cross to put those questions about fight and bottle to rest.
