Makes me wonder what they used for the cellar in Fig Biscuits and Inspirational Toilet Rolls filming because there does not appear to be any sign of a trap door behind the counter unless its around the other side hidden from the camera in this shot . I seem to recall Arkwright was near the till area when he gets Granville to influence Mavis using the pan to amplify his voice . I would not expect to see one in the hairdressers anyway so assume they must have created one for those scenes ?