This time last year, Mako Vunipola was back in his ancestral South Seas home – he is a part of one of Tonga's greatest rugby-playing dynasties – watching various friends and relatives indulge their passion for the game. A place on this Lions tour was beyond his wildest dreams. "I was just relaxing with my family, doing a little training and working out how to get into the Saracens team," he said. "Rhys Gill, a Welsh international, was ahead of me, so I knew I'd have to push myself."
Few props can have pushed themselves quite so far, quite so quickly. Twelve months on, Vunipola is one of the London club's star turns; his impact on the England scene has been entirely in keeping with his 20st frame; and he may just be on the brink of a place in the Lions front row for the first Test with the Wallabies, scheduled for Brisbane a week on Saturday. This is very decent going in anyone's language.
It is not in Vunipola's nature to shout the odds – when asked about being the new favourite to wear the most prized No 1 shirt in British Isles rugby, he repeatedly pulled up the drawbridge and left the question floating in the moat – but his performances on this tour have spoken for him. There is a chance that Alex Corbisiero, another prop of the red-rose persuasion, might scrummage his way into Brisbane contention, but Vunipola could seal the deal with another eye-catching display against the Waratahs on Saturday.
Pretty much the least experienced international forward in the original Lions party, he travelled here as the third of three loose-head specialists. Yet even if his elders and supposed betters, Gethin Jenkins of Wales and Cian Healy of Ireland, had not been crocked within a few days of setting foot in this country, he would have had them sweating over the potency of his ball-carrying and offloading skills.
Graham Rowntree, the Lions scrum coach, has worked hard on Vunipola's set-piece game, and the effort is beginning to bear fruit. "Graham has been a mentor for me since I was 18," he said, "and having him here has been a big help. But it also helps working with so many class players. You're bound to learn off them, to pick up a few tricks of the trade. Being around experienced guys like Paul O'Connell and Adam Jones… there are times in training when I pinch myself."
Scrummaging – or rather, the rival definitions of what scrummaging entails, allied to the way the set piece is refereed – is certain to play a big part in the Test series. The Lions will want to scrum long on their own ball, thereby forcing the Wallaby tight forwards to engage body and soul with a phase that is not wholly to their liking. The Australians, on the other hand, will want to be up and away as quickly as possible. Indeed, the Lions expect to see deliberate early engagements from opponents who would rather concede a free-kick than spend inordinate amounts of time peering deeply into their own fundaments.
The beauty of Vunipola, now he is properly conditioned, is his ability to play the Wallabies at their own open-field kind of game. As long as his tight work stacks up – and there has been plenty to write home about in that area in his Lions appearances to date – he could easily be the Test "bolter" of the tour.
"My form so far has been pleasing: the coaches seem happy with what I'm doing and I've had more chances than some people," he said. "But even though Gethin and Cian have gone home, it's not as if I'm the last loose-head standing. The coaches wouldn't have brought Alex and Ryan Grant [the Scottish forward drafted in as injury cover last weekend] out here if they didn't think they were good enough. I have to keep working, keep showing what I can do. You can't afford to think that the shirt is yours to lose. Every game is a clean slate."
In part, a Lions trip is a question of survival, as Vunipola will discover on Saturday against a pumped-up Waratahs pack prepared by Michael Cheika, who guided Leinster to the Heineken Cup title in 2009. One of the leading figures in that team, the current Lions No 8 Jamie Heaslip, offered a graphic account of what the tourists might expect.
"There'll be a lot of 'F-yous' and that kind of stuff because Michael is a fiery man," the Ireland captain said. "He's a passionate man – really passionate – and he wants his players to go flat out.
"He doesn't like people holding back, doesn't like them to hide. He's a hard nut. Some would say he's a madman at times. I wouldn't put it past him to have had his players hitting red tackle bags this week."
If Vunipola comes through that little lot, Brisbane will hold few terrors for him.