Indeed, it could be that two eras end at The Oval: that of the 74-year-old sage of Parramatta, and that of Australian supremacy in Test cricket. But when I suggest this latter theory to Benaud, the watchful eyes seem to narrow a fraction.
"I don't think so," he says. "They're being beaten by England, that's all. And you and I don't know how the Oval Test is going to go. Now, it may be that this era is coming to the end of the road, as eras do. Australia lost [Alan] Davidson, [Neil] Harvey, Ken McKay and myself in the space of a few months, but they kept going."
Might it, perversely, be a good thing for Australia to lose, in that the selectors will be compelled to introduce new talent?
The eyes narrow just a fraction more. "It's never a good thing for Australia to lose the Ashes."
OK, but is there any part of Benaud, one of the most successful of Australian cricket captains yet one of the least overtly partisan of Aussies, that hopes England prevail?
"No. What I would really like at The Oval is a result. It's been such a good summer, it would be a pity if a drawn match decided the Ashes. If Australia are good enough to win, they deserve to keep the Ashes even though they have been outplayed for much of the time. And if England win 3-1 it will be a result we can all applaud."
Looking back rather than forward, Benaud thinks that this has already been the greatest series he has seen, and will remain so even if the fifth Test is washed out.
"The best series I ever played in was the tied-Test series [Australia v West Indies] in 1960-61. As a commentator, I always had the feeling that the best series was 1981, but this one has shaded it, there's no question about that. I've never known such excitement. There are people, rational in their everyday lives, good at their jobs, used to writing cheques for 50 million quid, who can't bear to be in the same room as the picture. I know one young guy, a good young cricketer... We had an e-mail from his parents the other day saying that he went to his bedroom (during the nailbiting finale of the fourth Test) and pulled the covers over his head."
The "we" refers to him and his English wife, Daphne, whom he married in 1967, shortly after divorce from Marcia, the mother of his two sons. He and Daphne have homes in Australia and the south of France, indeed Benaud, characteristically, has scrupulously researched his French heritage (his great-grandfather, Jean Benaud, was a Bordeaux-born sea captain who arrived in Australia in 1840 and liked what he saw). In England, they always base themselves in the same suite at the same hotel near Marble Arch, and it is there that this encounter takes place, on one of the hottest days of the year, with Benaud, as ever, the epitome of cool elegance. Someone once described him as looking like a successful ladies hairdresser (retired), and I can't do better than that.
I ask what, for him, will be the enduring images of this remarkable cricketing summer? "[Andrew] Flintoff going up to [Brett] Lee at Edgbaston [to check on his well-being after England had won] was the best example of the excellent spirit between the sides, even though the competition has been fierce. And at Old Trafford, [Glenn] McGrath and Lee facing those last 24 balls. You could put them in 50 times with 24 balls to face and you'd get them out 50 times..."
What almost undid the Australians in Manchester - where Benaud enjoyed one of his finest hours as a player, captaining Australia to an improbable victory in 1961 and taking 6 for 70 in the process - was reverse swing. Benaud has admired the way in which Flintoff and Simon Jones, in particular, have found reverse swing so early in the innings, but, if he were the grand panjandrum of cricket (and cricket could certainly do worse), he would stop anyone but the bowler working on the ball.
To diminish the possibility of cheating? "No. To save time. To get the ball into the bowler's hand as soon as possible." A perfectly timed pause.
"But if there were to be a problem, the umpires would only have one person to have a chat with."
He would also change the front-foot law, which has bedevilled the Australian bowlers. 'There were 5,000 no-balls bowled before 1969, when the front-foot law was introduced, and there have been 27,000 since. It will stay the way it is but it seems to me to be a stupid law. In 1961 we had the most wonderful series, and there was only one no-ball in the entire summer, by Fred Trueman. The umpires told us, 'we want you to be landing on the bowling crease or thereabouts, so no bowler is taking an unfair advantage. If we feel he is then we'll warn him and then call him.' That's what happened to Fred. There was no time wasted, no 26 no-balls in an innings."
Benaud's manifesto for change is detailed in his absorbing new book, My Spin On Cricket. The book was completed in February, which makes these words, on page 266, impressively prescient. "Flintoff will be the key man during the Australian tour of England in 2005," the sage wrote. "If he fires, and the rest of the bowling attack are in top form, England have a real chance."
And so it has transpired, with, perhaps, a little input from Benaud himself. "I'll tell you a story about Flintoff, but it starts with [Ricky] Ponting, who wouldn't get up from the selection table until [Andrew] Symonds was in Australia's 2003 World Cup side. Having got him in the side, Ponting then flagged him down when Symonds came out at 90 for 4 in Jo'burg, with Wasim Akram and Waqar Younis really getting stuck in. Ponting said, 'I want you to listen to me, because I'm going to ask you to do something for me.' Symonds said, 'Yeah mate'. Ponting said 'No, I really want you to listen. I want you to be here at the end.' And he was. He scored 143 not out, and that changed Symonds' game. He's now a fixture in the one-day side. He's played in some Tests and he could play in more.
"Now, some time later Duncan Fletcher got me to make a presentation to Flintoff for some reason or another. It took place out on the field at Trent Bridge, and I said, 'I want to run something by you which might be of benefit to you. Never forget what Ponting did with Symonds, when he said 'be here at the end of the innings', and Symonds made 143 not out. Never forget that, now here's your silver salver'."
Benaud's story is interesting on several counts, not least in crediting the beleaguered Ponting with some smart captaincy. Although Benaud never lost a series as captain of Australia, he had to manoeuvre himself and the team out of trouble a few times. So what does Ponting need to do at The Oval?
"Persuade his bowlers to bowl better. There's never been a winning captain with a bowling attack that doesn't perform. But he has done his job as well as he can, considering that McGrath has been out for two matches, which has been absolutely critical, and [Jason] Gillespie has developed a technical flaw in his delivery stride, with his left shoulder pointing at mid-off the instant before he lets the ball go, instead of fine-leg.
"That's not Ponting's fault, but captains are fair game if they're not winning. Phil Tresidder, a great friend of ours who passed away in the last few years, covered the '61 tour for the Sydney Daily Telegraph, which was then owned by Sir Frank Packer. We won the Lord's Test with Harvey captaining because my shoulder had gone, then I came back for the Leeds Test, which we lost. Sir Frank sent a cable to Tresidder through the editor.
"It said, 'Sir Frank not happy with way team is performing. Need an article saying sack Benaud'. We pinned it up on the back of the door at Old Trafford and Tres always said it spurred us on to win.
"So the pressure was there, but it's much more intense now, with press conferences every night, and reporters saying 'my office has had 1,100 e-mails saying you should be sacked as captain, but only 700 saying you should be retained, what sort of comment do you have to make on that?' Well, when I was captain, there was no e-mail, and not all that many journalists covering the tour."
Ultimately, of course, the pressure on Ponting and his team derives from one thing: England have been better. The only Australian who has lived up to his (huge) reputation is the man who bowls wrist-spin and bats a bit, the skills that made Benaud, in 1963, the first cricketer to reach the double of 2,000 Test runs and 200 wickets. But there was nothing he could do that Shane Warne can't do, he says, and nothing he did that Warne can't do better.
Years ago, at a barbecue in Melbourne, Warne asked him for some advice, and Benaud passed on what he had himself been told by the legendary leg-spinner Bill O'Reilly: to forget about all variations until he had perfected a single stock ball, the fiercely spinning leg-break. "O'Reilly told me it would take four years. It took Warne two."
As the link between O'Reilly and Warne, and as much else besides, Benaud has a unique place in cricket's heritage, which makes it all the more regrettable that he is about to be lost to British terrestrial television, with Test coverage passing to Sky. Does he rule out a move to Sky? After all, he has already been on his fellow Aussie Rupert Murdoch's payroll, as a columnist for The News of The World.
"I won't answer that," he says. "All I'll say is that I've only ever worked as a free-to-air man, from 1963 to 1999 with the BBC, since 1999 with Channel 4, and with Channel 9 in Australia. And I have a new contract with Channel 9 for three years or more. They've said to me, 'it's not as though there's anything physical about what you do except climbing the stairs. What you have to do is keep your brain in gear.' Well, I have a few people I trust to let me know if there are any problems in that area."
As a free-to-air man, though, surely Benaud must bitterly regret the England and Wales Cricket Board's decision to sell the rights to Sky?
A wry smile. "I regret that I won't be working on British TV any more." And with that unusually evasive answer, he shakes my hand, accompanies me to the lift, and glides down the corridor, with not a hair nor a crease out of place.
My Spin On Cricket by Richie Benaud (Hodder & Stoughton, £18.99)Reuse content