Sportal.co.nz 11.Jan.2013Getty Images
Now he is. Twelvetrees, who trained with England during the autumn campaign, was officially promoted into the senior squad on Wednesday and is ready to make his mark.
The 24-year-old immediately set his sights on Brad Barritt's inside centre position and declared he can help England build on their All Blacks triumph by winning the Six Nations.
"I was excited like every other supporter of England to see the boys clicking and playing the way they wanted to. It was a revelation to beat the All Blacks," Twelvetrees told Press Association Sport.
"A lot of it was excitement and jealousy as well. It makes you feel you wanted to be part of the team and push forward as well.
"It has always been a dream of mine to be in the England squad and play for England. To officially be in the squad is fantastic news.
"You look around the squad at the quality of players we have and where we could go; it is important we kick on now into the Six Nations, not as a stepping stone but in terms of winning things.
"I am sure I can really help this England side and push Brad, who has been at the top of his game for a while. He is a very good player.
"I have got to be consistent playing for Gloucester and really take my chance in the training week before the Six Nations to express myself.
"I am in the squad for a reason but now I have to push forward."
Twelvetrees has long been earmarked for England honours but it is only since he joined Gloucester in the summer that he has been able to press his case with a consistent run of games.
His temperament for rugby at the highest level has not been in doubt since his Leicester debut against Ospreys in 2009, when he was given just 10 minutes' notice and ended up as man of the match.
Twelvetrees was at first five-eighths that day but his future with England is at second five-eighths, where he can be both a midfield playmaker and a ferocious defender.
Gloucester director of rugby Nigel Davies said earlier this season: "For me he's almost the perfect 12. He's got great distribution skills, he's massively physical and he's got a great kicking game.
"He's an exceptional player. There's no one else quite like him from an England view in a 12 perspective."
When England coach Stuart Lancaster announced his squad, he spoke about the importance of players offering 'a point of difference', an ability to spark something when the game is at stalemate.
Barritt has never missed a beat defensively for England since his debut last February and scored his first try in the victory over New Zealand.
But there are some who feel the national team could benefit from the presence of a more creative figure at number 12. Twelvetrees could be that figure.
"He's got talent across the board really. I've been very impressed with him," England backs coach Andy Farrell said.
"He is big boy, Billy, a big boy with a big presence. He has all the tricks of the trade that a 10 and a ball-playing 12 could have, but he is developing the balance of a game that you need to play at 12 in international football.
"If you look at the Leicester game a couple of weeks ago, there were a few coming down his channel and he was aggressive. He got stuck in, stood up for himself and showed a different aspect to his game.
"We have seen him develop massively. We're interested to see if he can step up to international football and translate that form he has shown for Gloucester."
Twelvetrees is joined in the senior England squad by Gloucester first five Freddie Burns, who made an eye-catching debut off the bench against the All Blacks.
Each credits the other for their form this season and it would not be a surprise if they are on the field together in an England jersey at some point in the not too distant future.
"We have similar personalities and similar ideas of what we want to do on the field. We know each others' strengths and it helps having that confidence with each other," Twelvetrees said.
"Being at Leicester [at the start of my career] really helped me. I learned a lot quickly but I couldn't put it into practice.
"I didn't get as much game-time there as I have done with Gloucester. I have played in every Premiership game, which has been really good for my development.
"Nigel and the coaches here have been really positive and that has given me confidence to go out on the pitch, try things and express myself.
"All season Mike Tindall [Gloucester's player-coach] has been very good at passing on his knowledge. He wants to back us young boys to show what we can do and express ourselves.
"Gloucester are an attack-orientated team and that has really helped my game."