The 24 year-old’s selection in Gatland’s 41-man squad is the culmination of a remarkable 12 months in the life of the Wexford man, who made his first Ireland start last June.
Now, after a season in which he became one of the first names on Joe Schmidt’s teamsheet, he’s likely to make his first Lions start this June against New Zealand.
“I’d have been very disappointed if I didn’t get it,” he now says. “But you never know if you did enough, if you performed enough, if you fit in the way the coaches want to play.
Furlong, unlike others, says he had no trouble sleeping the night before the squad announcement, although he did have a small amount of nerves when he sat down in the Leinster team canteen to watch the live unveiling with the rest of the squad.
Robbie Henshaw’s name was the first to have the team hollering, followed soon after by Johnny Sexton. Then it came to the forwards.
“Toby Faletau got read out, so it was in my mind that if it’s going to happen, it’s going to be next,” Furlong said, noting the alphabetical order of the squad announcement.
“That was a slow pause, and then they read out my name and obviously you’re delighted, all the lads clap you on the back. I took it in – then went training half an hour later.”
Furlong and Leinster could potentially play three more games before the Lions tour begins, with a home semi-final assured for the Guinness PRO12 playoffs.
Gatland may watch the games from behind his couch, with Furlong, Jack McGrath, Seán O’Brien, Henshaw and Sexton all carrying hopes of making the Test XVs.
But Furlong says the thought of an injury is not something he can allow to fester in his mind as the tour comes into sight.
“The day you start thinking, or worrying probably more than thinking, about injury is the day you probably go out and get injured,” he said.
Leinster will not risk Furlong’s fitness, but he’s likely to start all three games if the province make it to the Grand Final.
Those games may pale in comparison with a Lions test, but Leinster scrum coach John Fogarty knows the competitive animal within Furlong will keep him hungry for action.
It’s that desire, the former prop says, that has helped the Wexford man get where he is now.
“We always saw great things in Tadhg, which came from the type of person he is,” Fogarty said.
“He’s a guy who is a really good physical size, with a really good engine, a good profile in terms of injuries. He’s a tough, hard kid, he likes the pain of it; he doesn’t mind training hard, and being in pain in training sessions, and he doesn’t mind dishing it out, either.”
If he remains fit, Furlong is short odds to dish out some pain as the Lions’ starting tighthead ahead of England tightheads Dan Cole and Kyle Sinckler.
Furlong did his homework on the England pair ahead of the final Six Nations clash in March, and found plenty to admire in both players.
“I am a big fan of Dan Cole,” he said. “Sometimes when you are doing analysis, your mind drifts from what the loose-head is doing and you look at the tighthead and ask yourself what he is doing in certain situations.
“And you wonder if you could do that yourself.
“I find myself analysing Cole, wondering if I could do certain things like him or maybe certain things better or different to him. I would be looking at his process in the scrum, from the set-up to the bind to engage, it is very seamless and efficient. Very rarely does he get a bad entry into a scrum.
“That is huge for a tighthead. That is my work-on area a lot of the time.
“Kyle Sinckler is an animal around the pitch, he carries really, really hard. He has been scrummaging well with Harlequins. He is young and dynamic, he brings a lot of energy.”
Furlong is one of 25 first time Lions tourists, but has been given some advice by two-time Lion Jamie Heaslip.
“He said, ‘any opportunity you get to do something, excursions, to go out and have coffee with the sort of lads you usually wouldn’t hang around with or know from the other countries – do it,” he said. “Soak it all in. Take every opportunity to something new.”