The 18-year-old played a key role in helping Epsom College reach the Continental Tyres Cup final in March, the top tournament in the country.
And he opened the scoring with an early penalty in their defeat to Northampton School for Boys at HQ.
Arthur collected a record 48 first-team caps at Epsom, previously at Northcote Lodge Prep (now Broomwood School).
While at school he featured for Harlequins at age group level and later was in the Wales Under 18s squad.
He stepped into senior rugby earlier this year, playing for Cardiff RFC in Welsh Super Rugby, and Merthyr on loan as they won the Premiership.
But the teenager, who lives in Clapham and first picked up a ball at Battersea Ironsides, now has his sights on making an impact at OBR.
And he made a fine start with the fastest Bronco time on the opening day of pre-season, the 5ft 8in and 80kg livewire completing the course in an impressive 4m 36secs.
*We are delighted to have Arthur on board, joining fellow No. 9s Ed Hoadley, Ollie Hodgson and Matt Wickham.
A full welcome interview with Arthur will be out soon!
