His English accent is...
Impeccable. I'm American myself, but I can usually spot a faker. I can tell if an actor is really American/Australian/English when they speak.
This guy has the most convincing English accent I've ever heard from an American actor.
Although, after hearing that he lives in England, it's not all that shocking that he can fake it.
Take Christian Bale, for example. His American accent is perfect. But, he's also been living in LA since 1992, so of course he'd be able to fake it. He does it so well that when he uses his natural accent, he sounds a bit like he's faking being English.
Malarkey is the same, except it's to the opposite extreme. He's been in England for so long that when he talks naturally, he sounds like a Brit doing a semi-passable American accent.