You need more than an elongated inside-leg measurement to give Lomu the hurry-up, although every extra inch helps. You also require pace and nerve and the unbuttoned confidence of youth and the most recent addition to a fast-developing Wallaby pack possesses all this and more. At 22, Bowman is still in the process of filling out a frame to die for - 6ft 7in, the best part of 19 stones and counting - and, by way of rubbing it in, he is equipped with the handling skills of a threequarter-decent basketball player and the same natural farmworker's strength that gave the All Black forwards of yesteryear a certain, how shall we say, physical presence.
So, apart from absolutely everything, what does Bowman bring to this latest Wallaby vintage? "He brings us a lot of grief," said Rod Macqueen with the smile of a coach who knows he has struck gold. "Every time he goes near one of my players, he damages him. That's why we've nicknamed him `Disaster'. We went swimming earlier this week and Tom decided to try some backstroke. The next thing we knew, Ealesy had a black eye. I've never met anyone so bloody clumsy."
Not that Bowman looked remotely ham-fisted as he skated past Lomu in Christchurch in August. The Australian performance that day was something to behold; five minutes from time they were leading 27-9 and, despite two late New Zealand tries, it is doubtful whether any previous visiting side had so comprehensively marmalised the All Blacks on their own mudheap. "I kind of suspected it might be my day when the ball bounced straight into my arms from the kick-off and I had a rumble upfield," recalled the Sydney-based lock. "I seemed to be where the ball was throughout the game. Sometimes, you just get lucky."
And the try? "Jason Little slipped round the blind side of a ruck and flung out a chancy sort of pass that I had to pick off my toes. When I looked up, there was Jonah. Well, I didn't fancy my chances of going over him, so I decided to go round him. What can I say? Everything worked for me. It was a wonderful moment, but I took a fair bit of stick in the Sydney papers for my trouble. Second rows aren't meant to lurk out on the touchline and score tries at the corner flag."
Bowman came to rugby through his father, Roger, who farms land near the small town of Barraba, a short distance from Tamworth and about six hours north of Sydney. "Dad would regularly take me into town to watch the local side and I learned the ropes there as a junior before going off to Sydney to board at Scott's College. I played No 8 for a while and had the odd game at blind side, but to be honest I always felt more comfortable in the second row.
"From Scott's I went through the grades - Australian Schools, New South Wales Under-21s, the normal route - and then got myself picked for the Argentinian leg of last year's Wallaby tour. I didn't make it over here to Britain; I was one of six or seven guys packed off home after the Puma Tests. But it was a big thing just to be involved."
By the time a half-baked England party reached Queensland for the first international of their punishing sojourn among the southern hemisphere superpowers, Bowman had taken the final step towards fully-fledged Wallabydom. Was it possible to draw any real satisfaction from shoving 76 points up the stuffed white shirts of an opposing team patently unable to rise above their chronic outbreak of absenteeism? "Satisfaction? Gee, I should say. I thought it was great. My first Test and we put 76 on the English? I wasn't going to cry about it, that's for sure.
"I guess it was like everyone else's debut. People told me I'd run around like a chicken with its head off for the first five minutes and not remember a thing and that's pretty much how it was. I do recall it being a bit on the stop-start side, probably because we kept on scoring. But, in fairness to England, their defence was all over us for half an hour. We had to work hard for the initial breakthrough, then the backs cut loose."
A full-strength England will, he insists, prove a very different proposition this time around. But then the small gaggle of Brisbane survivors - Matt Perry, Austin Healey and Richard Cockerill - will find themselves confronting a very different Bowman. "I've got 11 caps in the locker now and I'm beginning to feel more relaxed, more able to play my game and more confident in the sense of bringing something of myself to the team. I don't feel like the new guy any more.
"John Eales has helped me so much; not in a `do this, do that, follow me' way, but just in his being there. I can't tell you the vibes I get just from looking up and seeing him right on top of the ball, doing his stuff. The thing with John is that he doesn't rush you. He appreciates that you need some time to grow into Test rugby and he's happy to let you earn the respect of the rest of the team in your own way and at your own pace."
That pace just happens to be lightning fast. Bowman has played more full Tests for his country than Super 12 matches for the New South Wales Waratahs and the acute Macqueen can take enormous credit for the success of his fast-tracking policy. The Wallabies have been searching high and low for a second lock since Rod McCall called it a day after the 1995 World Cup; Garrick Morgan, Warwick Waugh, John Welborn, Tim Gavin, David Giffin, Owen Finegan and John Langford have all been tried at one time or another. Not one of them did enough to make the shirt his own.
"The great thing about Tom is his honesty," says Macqueen. "He's playing a good few years above his age at the moment, but there's a lot more to come and he'll do everything he can to make sure he produces it." More to come? Heaven help us. Unless Eales takes his revenge on young Master Bowman in the nearest swimming pool, we may all be doomed.