On graduating from the National Film and Television School in March 2013, Arnold embarked on his first TV project, directing two episodes of the final series of BAFTA-winning channel 4 show, Misfits. He then directed the first four episodes of Russell T Davies’s new E4 show, Banana, and was named a Broadcast MagazineHot Shot 2014 for his work on both shows. In 2015, he directed two episodes of C4/AMC series Humans, which has become Channel 4's most successful original drama in over 20 years. A second series was recommissioned and a year later he returned to direct the opening block. He followed this up by directing an episode of British crime dramaBroadchurch for Sister Pictures. In 2017/18 Arnold directed Cleaning Up for ITV and Sister Pictures, having developed the project with writer and creator Mark Marlow. The six part drama show stars Sheridan Smith as Sam, a cleaning lady and devoted mother who struggles to keep her family together after becoming addicted to online gambling. In 2018/19 he directed Dark Money a four part drama for the BBC and The Forge. The drama stars actors Jill Halfpenny and Babou Ceesay. In 2020 Arnold directed the ITV miniseries Des.
Short films
On graduating from university in 2007, Arnold was awarded two consecutive digital short commissions through the UKFC and Screen WM. His film Stained, written by Ronnie Thompson and starring Ricci Harnet, Frank Harper and Craig Conway was selected for numerous film festivals, leading to nominations at the Midland Royal Television Society Awards for Best New Talent, Best Short Film and Best Director. Whilst at the National Film and Television School, Arnold's short filmEcho written by James Walker and starring Lauren Carse and Oliver Woolford screened at a host of international film festivals including Rotterdam International Film Festival, picking up awards including a National Film Award for Best Short in 2015. The film "centres on an outstanding performance from young lead Lauren Carse and a subtle, yet powerful story." His NFTS graduation film Charlie Says written by Frances Poletti and produced by Rob Darnell, premiered at Edinburgh International Film Festival in 2013. Based on an incident Arnold had on a childhood holiday, the film centres around themes of deceit and masculinity. Starring Elliott Tittensor and Christine Bottomley the film focus on a debut performance from a thirteen-year-old Conner Chapman.