It may well be that Grewcock will not start the Test against Australia at Twickenham on 12 November - not as a continued punishment for his alleged nibbling of the All Black hooker's digit during the opening match of a one-sided rubber last June, but because Simon Shaw of Wasps has stolen a march on him in the contest for a place in the coach's affections. But as sure as eggs are eggs, Grewcock will be in the match-day squad. Having delivered one of the defining performances of his sporting life in front of Robinson's eyes at the Recreation Ground on Saturday, any lesser reward would be an insult to the intelligence.
Steve Borthwick, who partnered Grewcock in the darkest depths of a magnificent Bath pack shorn of an open-side flanker for the entire second half because of the reorganisation resulting from the dismissal of the centre Andrew Higgins shortly before the interval, was barely less effective. His omission from Robinson's 30-man squad remains something of a brain-teaser - not least because the only contribution to the proceedings from Alex Brown, the lock promoted above him, was a stunning impersonation of the Invisible Man.
This is generally the way of it in the month before a major Test, of course. How many times has an England coach bestowed his favours upon an undecorated newcomer, only to see him plummet out of form from a Himalayan height? Mark van Gisbergen of Wasps, fast-tracked by Robinson on account of his apparent inability to commit anything resembling an error, disappeared into his own nether regions at Sale on Friday night after suffering the cruel brand of public torment specifically designed for full-backs. A few hours later, Brown also found himself on the wrong end of some ritual humiliation. It will be fascinating to see how these two players, uncapped and uncertain, confront their demons over the next fortnight or so.
"I wouldn't swap our two locks for anyone else's," pronounced John Connolly, the Bath coach, after a derby of two halves, the second of which scaled peaks in the way the first plumbed the very depths. As there was no need for him to say anything more on the subject, he spent the rest of his address talking up his diminutive hooker Lee Mears, who is also pressing hard for a first cap against the Wallabies.
"There is no doubt Lee is ready for Test rugby," insisted the Australian. "We've just seen Test-class rugby out there today, and at international level you have to get the basics - scrum, line-out, breakdown - absolutely right. Those are the bread-and-butter areas, and those happen to be the areas in which Lee is particularly good."
A coach discovers a thing or two about his charges when they are forced to play a man down - or, for 10 minutes on Saturday, two men down. Higgins, a fiery sort to say the very least, had already spent some time in the cooler for a head-high tackle on James Simpson-Daniel when he decided to stop Mike Tindall in his tracks in a fashion eerily reminiscent of Norman Hunter. Off he went, tail between legs. David Pearson, the referee, then flourished his yellow card in the direction of David Bory, who had committed the less than heinous crime of slipping in the side of a ruck.
Quite how a minor technical misdemeanour carries the same penalty as an attempted decapitation is mysterious in the extreme. Pearson has been promoted to the International Rugby Board's A-list for this season's Test programme. The regulars at the Rec now believe they know what the "A" represents.
Bath, six points ahead at 15-9 on the back of a fusillade of penalties from Olly Barkley and an astonishing drop goal from 50 metres-plus courtesy of Chris Malone, very nearly survived Bory's absence intact, but were finally exposed in the last minute of the Frenchman's penance. Rob Thirlby, as fast with ball in hand as he was hesitant in the less glamorous full-back duties, undid an outnumbered home defence with an old-fashioned in-out routine, finally swerving around Barkley en route to the left corner. Ludovic Mercier's touchline conversion put Gloucester ahead.
Yet Bath, with their locks to the fore and their powerful loose forwards, Andy Beattie and Isaac Fea'unati, not far behind them, took the fight to Gloucester at the set-piece and exerted sufficient pressure to earn Barkley a match-winning penalty three minutes from the end of normal time. They were forced to negotiate one last difficult moment when Luke Narraway galloped into their 22, but Tom Cheeseman, 50 per cent of a youthfully vibrant centre partnership completed by Ryan Davis, headed him off at the pass.
"We'd initially swung away from Cheeseman and Davis and gone for experience instead, but as it turned out, they found themselves out there opposite Tindall and Henry Paul," Connolly said. "My God, they did well."
Before he heads home to Australia at the end of next month, the Queenslander could do the world a favour and start picking his teenagers from the start.
Bath: Penalties Barkley 5; Drop goal Malone. Gloucester: Try Thirlby; Conversion Mercier; Penalties Mercier 3.
Bath: M Perry (R Davis, 24); F Welsh, A Higgins, O Barkley, D Bory; C Malone, M Wood; D Barnes, L Mears, D Bell (M Stevens, 53), D Grewcock, S Borthwick (capt), A Beattie, J Scaysbrook (T Cheeseman, 40), I Fea'unati.
Gloucester: J Goodridge (R Thirlby, 39); M Foster, M Tindall, H Paul, J Simpson-Daniel; L Mercier, H Thomas (P Richards, 55); P Collazo (T Sigley, 55), M Davies, P Vickery (capt), A Eustace, A Brown, P Buxton (L Narraway, 69), A Hazell, J Forrester.
Referee: D Pearson (Northumberland).