At 6ft 7in and 120kg Down becomes London Welsh's 24th new signing since the Club secured promotion back to the Aviva Premiership at the first attempt with victory over Bristol in the Championship final.

Down, 26, was spotted by Burnell as a 16-year-old while playing for the London Welsh head coach's former club Llantwit Fardre in South Wales. Recognising his potential, Burnell brought Down in to the Cardiff Blues system.

He trained with Cardiff in the summer of 2006, making his Cardiff debut in the pre-season match at Selkirk while still in the Blues Academy. His Blues debut came against Border Reivers in January 2007.

A broken leg suffered against Racing Metro in Paris in November 2011 interrupted his progress, but he recovered to fulfil that early promise and become an integral part of the Cardiff Blues pack, making 63 appearances for the region, including European experience.

Although uncapped at full international level, Down was called up to the Wales squad during the 2012 autumn internationals.

London Welsh head coach Justin Burnell said: "I always thought James had a huge amount of potential, which he obviously did.

"Coming through the Blues system he played alongside the likes of Bradley Davies and Lou Reed, who have both gone on to be full internationals. I still believe James has the potential to do that.

"He's played a lot of rugby in different competitions with Cardiff Blues and he's another fantastic addition to our squad.

"He's very much in the Matt Corker mould and like Matt he's got a great understanding of the lineout and the kick off, and he's very good in the contact area.

"I'm really pleased to have someone of James's calibre on board, pushing the players already within our squad and helping to add to the competitive edge."

The 2014/15 Premiership season will see Sunday afternoons at the Kassam Stadium in Oxford (kick-off 2:30pm) become synonymous with London Welsh (unless on occasions when dictated otherwise by television), with the club having committed to playing its home games at the Kassam Stadium for the next three years.