Since leaving LAMDA in 2006, Hadden-Paton has established himself as a leading stage actor. He was commended in the 2007 Ian Charleson Awards for his appearances in Romeo and Juliet at the Battersea Arts Centre and as John Worthing in The Importance of Being Earnest, directed by Peter Gill. His stand-out performances continued with Captain Jack Absolute in The Rivals at The Southwark Playhouse, as Hohenzollern in The Prince of Homburg at The Donmar Warehouse, and as Harry Villiers in the 2010 première of Posh at the Royal Court.
He is also notable for appearances in the Oscar-winning La Vie en Rose (2007), The Deep Blue Sea (2011), The Hollow Crown (2012), and About Time (2013).
In 2011 he appeared as Teddy Graham in the Olivier Award-winning revival Flare Path at the Theatre Royal Haymarket and as Jackie Jackson in a film adaptation of The Deep Blue Sea, both marking the centenary of their author, the English Playwright Terence Rattigan.
On television, he is best known for playing Bertie Pelham, the Marquess of Hexham, suitor of Lady Edith Crawley on Downton Abbey; their characters were married in the 2015 Christmas special that concluded the series. He has also starred in Midsomer Murders, The Amazing Mrs. Pritchard, Hotel Babylon, Silk, Waking the Dead, Drifters, Walter, Wallander, and Grantchester.
In 2016, he played the role of Martin Charteris in the Netflix series The Crown.
