The half-back, who made three appearances for his country in last year's World Cup, will join the capital club from Catalan Dragons on a two-year deal.

Barthau actually scored a try for the Dragons against his future employers at the Hive earlier this season and Broncos head coach Joe Grima believes his latest recruit will fit in nicely next season.

"I'm pleased we've secured William as he will fit into one of our key positions on the field," he told the club's website. "He's was impressive in the Dragons win over the Broncos in round nine and led them around the field.

"He should link up well with both Ray Nasso and Ben Farrar who he knows from their time in France.”

Barthau, 24, is excited by the opportunity to move to London and is determined to help the club clinch a return to Super League at the first time of asking.

"I'm looking forward to joining the Broncos as it will be good to learn a different system and to play with different players,” he said.

"The challenge is to get into the top four and then play four Super League clubs to show we are ready to play in Super League again. I know that I can play my part in helping the club achieve this.

"I'm really motivated to be part of a winning culture that Joey Grima is creating, and I'm also looking to improve individually during my time at the club.

"I already know Ray Nasso and Ben Farrar who have lots of talent and I'm looking forward to playing alongside the young talent that is being developed in London.”

Meanwhile, the Broncos have announced James Duckworth has been released for the remainder of his contract to enable him to move back up to Leeds and play for Hunslet Hawks. Maxime Herold has also left the club, allowing the Frenchman to return home and continue his recovery from a broken arm.