Now in his eighth year as national wicketkeeping coach, Knott has become used to this sort of predicament but his sense of irony and perpetual enthusiasm gets him by. He would find something complimentary to say about a cross-eyed darts player (''nice wrist action''). Thirteen county keepers receive regular attention from England's most distinguished stumper (95 Tests), Russell and Alec Stewart most of all. Only three - Karl Krikken (Derbyshire), Rob Turner (Somerset) and Adrian Shaw (Glamorgan) - have had no direct assistance.
His No 1 priority this season has been to fine-tune Stewart's glove work at England's pre-match training, but away from Tests, his schedule is hectic. This weekend, he will be at Northampton checking on Russell Warren's form, also filming the opposition keeper Martin Speight, before driving up to Durham for a one-to-one with him, then head back to Canterbury via Warren Hegg at Old Trafford. All have been earmarked by the selectors as future internationals of one form or other, as has Leicester's Paul Nixon, with whom Knott worked last week.
``It's a very interesting but difficult job,'' he said, stirring a cup of murky liquid for the 18th time, ``helping different people competing for the same spot. You learn so much and sometimes you see X do something and you feel guilty thinking 'Phurr, that really would help Y'. You have to be neutral, though, and ultimately the reason you coach is because you want to see people justify their talent, play to the very best of their ability.''
Knott's sphere of influence is the nearest thing to cloning in professional sport. The tendency for English keepers to position themselves slightly askew to the wicket, facing mid-off, was Knott-initiated, for instance. It originated from his practice sessions with Russell. ``The higher level you go, the more likelihood of batsmen getting outside edges, so we worked on opening his stance to give him a better view and make it easier to dive right. I have suggested it to the others - some saw Jack using it on TV, too - and most seem to like it a great deal.''
Russell is the ultimate Knott clone, of course. He recognised his destiny the moment he saw Knott take a brilliant diving catch on television at the Headingley Test in 1977, and through incessant contact has adopted many of his mannerisms. They are both faddish eaters who exist on carbohydrate and cold tea, on the field subscribe to the mantra that ``It's not how, it's how many'' (Russell's quirky batting style is Knott-fashioned) and do dotty things to their equipment. This includes starching their collars to keep them turned up (for posture and as protection from the elements) and sticking bits of shirt on their sunhats to weight them against the wind. ``Jack and I are different in a few ways,'' Knott reflects. ``Politically we are. I don't think about war quite the way he does, and I can't paint for nuts.''
He is imaginative, though. He has developed an intriguing variety of routines to improve a wicketkeeper's agility and reflexes, almost as if his own raison d'tre is to ensure the eventual extinction of the bye, and employs some unusual accessories. Like shower mats. Shower mats? ``Well, I wanted the ball to deflect quickly off the ground at an angle, so I tried bouncing it off those ribbed car mats but they were quite small and easy to miss. Somebody suggested using the rubber mats out of the showers and they're wonderful, like a flat slip cradle.''
Such aids were not in evidence at the Oval before the sixth Test. Knott fussed animatedly about Stewart as he kept to Phil Tufnell a yard in front of the stumps. ``It gives Alec a harder length of ball to take, bouncing so close to him,'' he explained.
After a while, he stood at the crease and swished a bat deliberately close to Tufnell's deliveries, giving both bowler and keeper something else to focus on.
Then, after an encouraging word with Tufnell about his line and degree of spin, Knott retired to a distant part of the outfield to underarm Stewart countless one-handed catches off a three-pace 'run-up'. They were still at it long after all the other players had gone in.
``I carry Knotty about in my bag,'' Stewart said afterwards. ``I've worked with him intensively since '94 and if you look at videos of my keeping five or six years ago and compare them with now, you'd see a big improvement. That's all down to him.''
Video is Knott's faithful accomplice. The office in his house contains more tapes than a branch of Blockbuster, all shot or recorded himself and each neatly labelled. Stewart's and Russell's take up two shelves. Knott is glued to his sitting room TV during Test matches, and is then embroiled upstairs, fastidiously copying every ball that, say, Stewart caught on the second bounce on to another tape. The England and Wales Cricket Board have hired a video-computer boffin this summer to help out. In the evening, he will phone Stewart to discuss the play and offer ideas.
``Alec's an amazing worker on the game,'' he says, still stirring his tea. ``He'll try most things I suggest - different stances to left-arm spinners bowling over the wicket, for example - and sometimes he gets really excited.
``That's the key to keeping - maintaining the thrill of being out there, wanting the ball to come even straight after dropping a catch.''
Russell excites him most of all, though it would jeopardise his impartiality to admit it. ``I remember seeing him keep for the first time, in 1982. Phew, stood up he was brilliant. Bright, lively, sparkly. I always look to see if their eyes sparkle. The thrill for me of seeing something you've worked on succeed is as big as playing: Jack catching Rhodes at Jo'burg, Alec grabbing Lara one-handed at Lord's. Terrific.''
Among all the neuroses about England's batting and bowling skills, it is reassuring to know the art of wicketkeeping is in such safe hands.