Owen Farrell is in a striking mood today. It is almost surprising to compare how relaxed and amiable he appears in contrast to the intense and often fiery man who plays for Saracens and England. There is a new lightness to Farrell, at least in the comforting surrounds of Saracens’ training ground in St Albans, and it is only when transcribing his words that it becomes clear how a concentrated ambition beats even more strongly inside him.

Amid the chit-chat about his love of watching sport on television and moving out of home so he can be looked after by his girlfriend, the recurring theme is obvious. It resonates so often that I count 16 separate occasions when Farrell uses the words “improve”, “improving” and “improvement”, or the short phrase of “get better”.

“All we’ve ever tried to do is get better,” Farrell says as he shrugs off a compliment for the way in which, 10 days ago, on his return from injury, he inspired Saracens to subject Toulon to a rare lesson in attacking rugby, and sealed the French club’s first home defeat in the European Champions Cup. “We know what we’re good at but we want to improve in every area of the game. We did well against Toulon but we were a long way from perfect.”

Farrell scored 16 points and his coach Mark McCall, who described him as the best player in Europe before the match, said: “The way Owen played was remarkable.” On Saturday, in his second game since injuring his back in pre‑season training, Farrell kicked 19 points, and created so much space for his backline, as Saracens completed a 44-26 European thumping of Scarlets.

“I enjoy giving this everything,” Farrell says simply as he relishes playing again. “It’s an obsession of mine and something I love doing.”

That second sentence contains the crux of Farrell’s approach while explaining how he has dealt with the tumultuous past year. Last October Farrell and English rugby were at a terrible low point after their humiliating World Cup. Twelve months on, following a grand slam and a 3-0 series whitewash in Australia, they have won 10 Tests in a row. Eddie Jones, the coach who sparked the transformation, hails Farrell as “solar-system class”.

Owen Farrell of Saracens surveys the scene after the victory over Toulon. Photograph: David Rogers/Getty Images

Five months ago Farrell also won the Premiership and European Cup double with Saracens but success has sharpened his appetite. Past disappointments also underpin these achievements. Farrell remembers how, two years ago, he and Saracens endured a double blow. A week after they were crushed in the European Cup final by Toulon, the Premiership title was snatched away when Northampton were awarded a controversial try in the last minute of extra-time.

“The disappointments probably make the big wins happen in the first place,” he says. “It’s not just that the lows make the highs more meaningful. They actually help you figure stuff out. You have to work out where you went wrong and what you need to do to get better. We’ve done that at Saracens and obviously things have changed at England. The main thing is that we’ve improved.”

The old southern hemisphere jibe – that England are satisfied too quickly by a few wins – is redundant in Farrell’s company. As the autumn internationals loom with Tests against South Africa, Fiji, Argentina and Australia, Farrell talks plainly: “We’ve still got a long way to go. We’re by no means anywhere near where we want to be. Our improvement is exciting but it’s not enough.”

Any temptation to get carried away is curbed by the history-making All Blacks. On Saturday New Zealand became the first team to win 18 Tests in a row, beating Australia 37-10, and the gulf between them and every other rugby‑playing nation is obvious. Yet Farrell sounds more inspired than intimidated. “They’re a brilliant side and brilliant to watch. Obviously every team is different and you don’t want to try and be them. But you’ve got to figure out your own way and work hard to get to that level. I saw them against South Africa [when New Zealand scored nine tries while hammering the Springboks in Durban] because you watch every big game and try to learn from it. New Zealand were very good. It was a clinical performance and that’s the standard they’ve set.”

Jones has been measured in analysing England’s progress. He also enjoys his reputation as a coach whom his own players often fear. Does Farrell feel any trepidation? “What you feel more than anything is that you want to perform. You want to do well for him. He works hard to create that environment. And we try to create it as a team – so you drive yourselves.

“I wouldn’t want this to come across the wrong way … but I wouldn’t say it’s comfortable playing for [Jones]. There’s no way you’re going to ease off.”

Before he began working with Jones had he heard about the Australian reducing some hardened Test forwards to tears? “You always hear stories but I can only speak from my experience. I was here when Eddie was at Saracens [as a consultant in 2006]. I was a young lad in the academy. I actually played my first game at Saracens under him – against Scarlets. We lost.”

Owen Farrell makes his Saracens debut against Scarlets in October 2008. Photograph: John Gichigi/Getty Images

Farrell smiles as he recalls how, in October 2008, 11 days after turning 17, he became the youngest player to appear for an English Premiership club when Saracens picked him in an Anglo‑Welsh Cup fixture. “I remember those times with Eddie really well. He was brilliant with me. Really brilliant. My experience of him then and now has been great.”

Jones can still be brutal. He picked Farrell at fly-half against Australia in June but, after 29 minutes, with Luther Burrell struggling defensively at inside centre and England 10-0 down in the first quarter, Jones made a dramatic substitution. Burrell was taken off, George Ford was sent on and Farrell moved to centre. England won 39-28 and Farrell scored 24 points. The early replacement seemed cruel to Burrell but, in the blunt terms of Test rugby, it was justified.

“I guess it did surprise me,” Farrell says. “We spoke about it afterwards but that’s what needed to be done. Thankfully we ended up winning. You don’t like to see that happen but while you’re playing you just go: ‘Yeah, right, let’s get on with it.’”

I wouldn’t want this to come across the wrong way … but I wouldn’t say it’s comfortable playing for [Jones]

In all Jones’s other matches as England coach, Farrell has started at inside-centre. He retains the No10 shirt at Saracens. Does he prefer his club position? “I’d say so. I’d say I am a fly‑half. As regards being 12 for England I’ve not tried to play any different. I guess I’ve been like another 10. Obviously you do some things differently and you might not have your hands on the ball as much – but you’re still in the game and constantly communicating. You’re happy to fit in wherever you’re wanted.”

Any frustration Farrell feels at not being picked in his favoured role is offset by the pleasure of playing in a winning team with his close friend. “Oh, it’s great. Me and George have played alongside each other a lot. We did all the age groups together and we’re very open about how we see the game. We talk to each other and it works well.”

Farrell and Ford have similar backgrounds – the sons of rugby league men [Andy Farrell and Mike Ford] who became respected union coaches after moving from the north and ending up in the leafy Hertfordshire town of Harpenden. Apart from playing rugby together every day, either at St George’s School or in the street, Ford sometimes did Farrell’s French homework.

“He’s probably cleverer than me so he would help me out,” Farrell quips, “even though he was the year below me. So I like playing alongside George. The main thing is I’ve tried to get better at everything – that includes the attacking side, being a threat and taking people on.”

Farrell has endured enough bruising defeats to make him a rounded player – but his team-mate Maro Itoje has yet to learn the same harsh lessons. In his sensational first full season with Saracens and England, Itoje did not lose a single game he started. This season Itoje’s perfect record has suffered a single blemish as Saracens lost unexpectedly against Harlequins on 24 September – the then‑injured Farrell’s 25th birthday.

Owen Farrell scores the winning try against Australia in Melbourne. Photograph: Scott Barbour/Getty Images

Itoje is only 21 and, despite fracturing his hand last Saturday and being ruled out of the autumn internationals, he must think it is easy winning Premiership, European and Test matches? “Yeah,” Farrell says wryly, “it’s the norm for him.”

Winning will not last forever – it never does in sport or real life. “No, of course,” Farrell says before he laughs. “Although I hope it does for Maro because I’ll be playing with him. He also went to St George’s and ever since he’s been at Saracens the most impressive thing about him is that he’s took everything in his stride. He’s never been in awe of anything. It doesn’t matter who is in front of him, he thinks he can dominate them. He might not even think like that – he might just do it.”

Farrell and Itoje are likely to be important figures for the British and Irish Lions in New Zealand this season. Farrell is understandably more comfortable talking about the 2013 tour of Australia than speculating on his possible role against the All Blacks. “I loved it,” he says of the last Lions series. “It was brilliant – especially as we won. I only got on at the end [as a substitute in the decisive third Test] but to be involved in the whole thing and to play with some special players was incredible.”

Has he allowed himself to think ahead to New Zealand? “Not at the minute. I’ve just played my first games after injury and I’ve focused on getting fit. Now I’ll try my best to improve my consistency.”

Part of that improvement is built around Saracens inviting different people to address the squad. “We’ve had some amazing people talk to us. The Brownlee brothers this month and people as different as AP McCoy, business guys and hostage interpreters. AP and the Brownlees have been at the top a long time and it’s cool hearing how much they put into it and how much drive they have. It makes you want to have the same drive.”

Farrell has also found a way to control his temper. “Yeah!” he exclaims. Presumably he is still boiling away on the inside? “No, no, not any more,” he says, laughing. “Rugby is a tough game. You’re never going to whisper on the field are you? I’m pretty loud – but I figured out it’s important being clear for 80 minutes and not switching off and having a little moment to yourself when you’re going mad. As soon as I got my head round that I was fine. I’ve improved.”

He flashes another grin after using his favourite word. Farrell knows we will discover how much he, Saracens and England have improved by the end of this long and testing season.