Having trailed 12-3, Bath won 41-15 and thereby not only put into perspective the l46 points Quins had amassed in thrashing West Hartlepool and Sale on the previous two Saturdays but also opportunely demonstrated what it is the Rugby Football Union will be missing if clubs and union break asunder.
This is no longer a remote possibility - as it has seemed through most of the season - but a clear and present danger as the disagreement over how to finance and administer professional rugby reaches the point of schism. The RFU is so panic-stricken at the suddenly increased obstreperousness of its First Division clubs that it has hastily called a media briefing for tomorrow at Twickenham to try to set out a case that has hitherto gone by default.
After all these months, it is almost too late. However unpleasant the personalised campaign against Cliff Brittle, the chairman who was thrust upon the RFU executive by a mass membership untouched by professionalism, he has been identified by the major clubs as the obstacle to progress. It would be idle, absolute folly in fact, to pretend - as the RFU president, Bill Bishop, in effect did last week with his public vote of confidence in Brittle's negotiating conduct - the problem did not exist.
With this season having less than a month to run, the antagonists have reached such an impasse that no one knows even what fixtures they will have next season. This unprecedented vacuum betrays the astounding insouciance with which the RFU has addressed the problems - a pounds 1m-a-year problem for each club - of those directly touched by professionalism.
It is an unholy mess, so much so that in current circumstances English rugby scarcely deserves the distinction of having the likes of Bath, or Harlequins for that matter, as its standard-bearers. Between them at the Rec they provided rugby of a thrilling and heroic dimension which left the victors four matches (the first at Gloucester on Wednesday) from winning the league for the sixth time in its nine seasons.
The match was a fascination not just for the bravura rugby with which Harlequins started and Bath finished but also for the astuteness with which Bath adapted their tactics in order to counter Quins' highly effective running game. Bath went smoothly from Plan A, no-kicking sevens-style rugby which consistently lost them territory and the ball, to Plan B, hammering into Quins at close quarters and draining their energy with a forward assault that would have been roundly condemned had it been perpetrated by Leicester.
There was a difference, though. For Bath, it was merely a means to an end and even when the hand-to-hand combat was at its fiercest they still had a keen eye for when and where to move into the open. One try by Rob Kitchin within two minutes and another by Paul Challinor 12 minutes later had come as an unwonted early shock but there is no finer response to a crisis than Bath's. If only the same could now be said of the RFU.
The whittling-away was done by the first five of Jonathan Callard's penalties and Bath were finally on terms 13 minutes into the second half. From the next kick-off they created a breathtaking try for Jon Sleightholme and thereafter steadily turned a precarious lead into a handsome one, Phil de Glanville and Jeremy Guscott adding two more tries as suitable embellishments to 32 unanswered points.
"I'm exceptionally pleased with that performance," said John Hall, Bath's playing director - which coming from him was verbalised ecstasy, especially at such a difficult time. The transfer market opens for business on 6 May and this week Hall will try to dissuade the England forward Ben Clarke, an absentee on Saturday, from following the Cardiff half-backs to Richmond; Adrian Davies and Andrew Moore are expected to be the subject of an announcement on Wednesday.
Meanwhile, Hall expressed his usual post-match confidence that his outstanding squad would stay together. So did Dick Best, Harlequins' director of rugby, though his squad were shown by events at the Rec to be considerably less outstanding either than Bath's or than they had seemed when overwhelming West Hartlepool and Sale. "It's the first time for quite a while that we've had a juggernaut coming towards us," he said. "They were brutally effective."
Europe none the less beckons, always supposing there is to be a Europe. "It may be a triangular tournament in Jersey," Best said in an appropriately sardonic reflection on a ludicrous state of affairs. There are plenty of people on the RFU side of the debate who will privately confirm that a settlement would - and should - by now have been reached but for the paroxysm that has gripped the English game (but nowhere else) since the dread word "professional" became part of the official vocabulary.
It gets worse: the RFU's demand for a 60 per cent share of the next Five Nations television contract has the Welsh, Scots and Irish - used to a straight four-way split - so worked up that they are even talking of expelling England and replacing them with Italy. There is also talk of getting Brittle to step aside, of which there is no chance, at any rate not voluntarily. He has a mandate, you see.
"It seems to me that every time we want to get to the negotiating table we are being blocked," Hall said. "The message I am getting from Twickenham is that they want to get on with it but it seems to me that a certain Mr Brittle is very obstructive to our case. As each day goes by, I get more pessimistic."
This may be awfully unfair on Cliff Brittle but the very fact that Hall should be asked about this subject after Bath's finest performance of the season tells its own baleful tale. English rugby is on the brink.
Bath: Tries Sleightholme, De Glanville, Guscott; Conversion Callard; Penalties Callard 6; Drop goals Catt, Nicol. Harlequins: Tries Kitchin, Challinor; Conversion Challinor; Penalty Challinor.
Bath: J Callard; J Sleightholme, J Guscott, P de Glanville (capt), A Adebayo; M Catt, A Nicol; K Yates, G Dawe, J Mallett, M Haag, N Redman, S Ojomoh, E Peters, A Robinson.
Harlequins: J Staples; D O'Leary, W Greenwood, P Mensah, S Bromley; P Challinor (C Wright, 69), R Kitchin; J Leonard (capt), S Mitchell, A Mullins, A Snow, P Thresher, G Allison (C Sheasby, 41), M Watson, R Jenkins.
Referee: J Pearson (Yarm).