The set was built in my back garden. Although obstructed by a garden wall, essentially the replica window was facing the window that it was replicating. In fact the male character could quite easily see the replica of his own window being created.

On the night of filming I was about eight feet up a ladder with a video camera when the male character happened to arrive home and park just the other side of the wall. There was something quite right about the fact that the person and environment I had intervened with all those months ago was now intervening with the theatrical reenactment of that moment.