There they were imagining it had been a routine cup win, having succeeded where Bath and Orrell had failed by beating Waterloo 21-14 and progressing into today's Pilkington semi-final draw. Cracking tries by Mike Wedderburn and Kent Bray reflected their superiority.
Both sides agreed the victory was deserved. The Harlequins manager, Jamie Salmon, even expressed the hope that Waterloo would be promoted to join Quins in the First Division next season. All very nice - and quite out of keeping with the recriminations that reverberated round Blundellsands.
First Waterloo accused Harlequins of sharp practice (almost literally so) in wearing long studs which are specifically barred by the Laws of the Game. The second-half procession of Quins temporarily dismissed by Stewart Piercy, the referee, to get them changed supported this contention.
Not that Piercy, who has been elevated to the Rugby Football Union's top 10 this season, would explain. Clarification, please? No answer, came the stern, utterly useless reply, though, as he was wired for sound for television's benefit, we were able to ascertain that when Jason Leonard followed Brian Moore to the sidelines Piercy told him they were not the boots he had inspected in the dressing-room beforehand.
Jed Poynton, the Waterloo team manager, said that immediately after the match Piercy had been very upset and indicated to him that he would be reporting the matter to the RFU. We will have to take Poynton's word for that since Piercy would not talk to Salmon either. Further elucidation became impossible when Salmon, a former England and New Zealand centre, then gagged his players.
The serious allegation from Waterloo is nothing less than that Harlequins first presented themselves for inspection wearing correct studs and then surreptitiously switched them for longer, sharper studs which are worn, quite legitimately, in rugby league.
'It's the oldest trick in the book and really dangerous,' said Mike Hayton, a Waterloo replacement who watched the comings and goings in the dug-out. Hayton is a doctor. 'Quins deserved to win but it's tainted if someone goes and breaks the regulations,' Poynton added. 'It's the same as if it's illegal play on the park. It's sharp practice just as if they'd played an ineligible player under the regulations. You expect at this level that you abide by the rules.'
To which Quins retorted that Waterloo had pulled the same stunt before playing Orrell last month. 'We came prepared, did our research and we knew that scenario was going to happen,' Salmon said. 'It's pretty cheap on their part.' Even so, Salmon added that Quins would institute an inquiry this week. 'I have to say I don't know what the rules are in relation to studs. I don't go round checking forwards' boots.'
With Paul Hackett, the Waterloo hooker, giving Piercy a steady stream of advice, Moore was sent to change studs at half-time. Leonard followed, and when Alex Snow came next the spares had run out and he had to run in his stockinged feet to the dressing- room to find some other boots. Pantomime.
They are also ultra-sensitive about foul play at Waterloo after ridding themselves of their own reputation - and are prone to exaggeration. 'I've never seen injuries like that in 10 years playing rugby at this level,' Hackett said of the marks on Austin Healey's back - though when Healey put himself on parade it was clear Hackett had never seen the backs of Mike Teague and Mike Hall after the Queensland game on the 1989 Lions tour.
It was no exaggeration that Steve Peters needed nine stitches round his nose after being caught by one of the offending studs. And the concussion Steve Swindells suffered, allegedly in an off-the- ball elbowing, played a debilitating part in the missed tackle which helped Wedderburn on the way to his spectacular try.
Salmon, however, was incensed at the welter of complaints, citing Richard Langhorn's broken cheekbone as evidence to the contrary. 'You can't paint us as the dirty party in this. There's no way we have ever been labelled a dirty side. There's no way you can say we were the instigators of foul play.'
To which Derek Murphy, Waterloo's chairman of rugby, rejoined: 'All penalties we saw for foul play in the game were awarded to Waterloo and against Harlequins.' Indeed, it was Winterbottom, Snow and Leonard who were the ones in receipt of Piercy's strictures.
Strangely enough, it did not seem so bad at the time and amidst all the kicking (of the ball, that is) there was some decent rugby. A breathless start by Waterloo brought a try when Chris Saverimutto dived in as a Harlequin scrum ball reached the line and, although Quins' response was more decisive than that of Bath and Orrell had been, Waterloo ended the game rather the stronger.
Quins were increasingly disrupted by the studs affair and the persistence with which they were penalised by Piercy. But by then Wedderburn's try, at the first half's last gasp, had been followed by Bray's and Quins were more or less safe.
In instigating it Leonard, who had just changed his footwear, scattered tacklers exactly as England would like him to do, and Mark Russell did the same before the ball was switched to the left through Roux, Challinor, Sheasby and Thompson.
A crowd of 6,600 - the first of this magnitude at Blundellsands since Waterloo beat Bedford in the 1977 semi-final - deserved much more of the same passing fancy. But, one way or another, the inexorable winner of this match was the boot.
Waterloo: Try Saverimutto; Penalties Handley 2, Swindells. Harlequins Tries Wedderburn, Bray; Conversion Challinor; Penalties Challinor 3.
Waterloo: S Swindells (A Handley, 40); A Healey, M Craig, N Hill, G Fraser; I Aitchison, C Saverimutto; M Beckett, P Hackett, S Peters, N Wilkinson, N Allott (capt), A Ireland, S Beeley, P Buckton.
Harlequins: K Bray; M Wedderburn, W Carling, G Thompson, E Davis; P Challinor, J Roux; J Leonard, B Moore, A Mullins, A Snow, R Langhorn (N Killick, 44), M Russell, C Sheasby, P Winterbottom (capt).
Referee: S Piercy (Goole).