Monday morning in the small Essex town of Coggeshall, and in an unassuming building that used to be a laundry, a man named Barnaby Smyth is trying to sound like a horse. Trying and succeeding, uncannily. Not neighing or whinnying, just making the sound of the hooves on the ground.

Up on a big screen on the wall of a windowless room is an armoured knight astride a white warhorse. It’s Richard III, as it happens, accompanied by a gaggle of guards, also armoured and mounted. It’s a scene from The Lost King, Stephen Frears’ upcoming film about the woman who, after 30 years of looking, discovered Richard’s remains under a Leicester car park.

Smyth squats in front of the screen, staring intently. In front of him on the floor is a square of compacted earth with a microphone