As reported in the Radio Times, Merrick will be playing a character called Brains (revealed by his spoiler-blowing representatives United Agents). In the episode Brains no doubt be using his smarts (unless it’s an ironic name and he’s just hurling whatever he has in his pockets at Cybermen) as he joins a band of misfits played by Warwick Davis, Jason Watkins and Tamzin Outhwaite who come face to face with the Doctor’s old foes.
Speaking of the episode recently, Steven Moffat commented:
With one of the all-time classic monsters returning, and a script from one of our finest novelists, it’s no surprise we have attracted such stellar names as Tamzin, Jason and Warwick.
Apart from his role as Alo Creevey in the fifth and sixth series of E4 Yoof drama Skins, Merrick also appeared in BBC One sitcom In with the Flynn’s as well as an upcoming appearance in Doctor Who scribe Richard Curtis’ 2013 rom-com In Time, staring fellow Doctor Who co-star Bill Nighy.