By Mitch Phillips

LONDON (Reuters) - Not long ago the only time rugby fans in Wigan got excited about a trip to London was for the Challenge Cup final at Wembley but now the town that lives and breathes league is almost ready to be twinned with Twickenham.

The latest player to complete the previously unthinkable transition to union is Joel Tomkins, who will make his England debut against Australia on Saturday.

At exactly the same time (1430 GMT), his younger brother Sam will be turning out for England against Ireland in the rugby league World Cup at Huddersfield.

Their proud parents have opted for Twickenham to complete the Australian double having watched Sam last week when England lost to the Kangaroos in the opening game of league's showpiece event at Wembley.

Such a fluid interchange between rugby's two codes would have been unimaginable only 20 years ago, when they were run on fiercely parallel lines and when Wigan's Central Park and Twickenham might as well have been on different continents.

Wigan, a small, fiercely, proud former industrial town in the shadow of Manchester, was known throughout the world for its rugby league team and revelled in its gritty image.

Leafy Twickenham in south-west London was considered the home of the worst kind of southern union snob and the two camps, having co-existed firmly at arm's length for a century, showed no intention of making friends.

Union's move to professionalism in 1995 changed all that and a trickle of crossovers began, albeit with only limited success.

But Jason Robinson, the twinkle-toed winger who had lit up league playing for Wigan and Great Britain, showed how the cream could rise to the top in either code when he switched seamlessly and played a key role in England's 2003 union World Cup victory.

Since then the Wigan to Twickenham conveyor belt, while not exactly in overdrive, has still been a rich source of talent for the 15-man code, and Tomkins found himself amongst some familiar accents when he met up with the England squad this week to prepare for the first of three November internationals.

Assistant coach Andy Farrell spent most of his career at Wigan before switching to union and playing in the 2007 World Cup final, while his son Owen is now England's regular flyhalf.

Winger Chris Ashton was a former Wigan team mate and friend, the two 26-year-olds hailing from the same class at high school.

TOWN STOPS

"As a kid in Wigan there's really no other sport and you grow up with a passion to play rugby league for Wigan," Tomkins told reporters. "On Friday night the whole town stops - nobody wants to be a footballer - and I had no interest at all in union.

"Once Chris moved to union (in 2007) I started to follow it a bit more and it whetted my appetite but it was only when I got a bit older I began to think about whether my skills were transferable."

Given that an injury to another league convert, Brad Barritt, partly opened the door for Tomkins to form a new midfield partnership with Billy Twelvetrees, and that he edged out another convert in Kyle Eastmond for the 13 jersey, it is clear there is plenty the league men can offer.

England's defence will benefit his presence while his aggressive running and ability to create space might bring the X-factor to the midfield that has been absent for so long.

"It was a goal of mine to get into this squad, that was a major factor in switching codes, to play international rugby in front of 80,000 at Twickenham, and ultimately the World Cup," said Tomkins.

"I've played in big games, a couple of finals with Wigan, league internationals for England, but Saturday will be the biggest crowd and I'm really excited."

Despite his league pedigree, Tomkins was not too proud to start at the bottom after his move, learning the game with the Saracens second team in front of crowds of only a few dozen.

Mastering the breakdown proved the biggest challenge initially and, once he had made the first team, learning when, and more importantly when not, to deliver his trademark offload that has opened the way for so many tries over the years.

"It was probably only after the first full pre-season of last season that it began to feel instinctive," he said. "Once you feel comfortable at the breakdown you can relax and start to enjoy it."

(Editing by Ken Ferris)