 The entire piece is improvised, Mike Leigh (qv) worked with each  actor separately to create a character with a history from birth to  the present day. Once the characters were fully formed he placed  them in the situation and let the action commence. Probably about  90% of each character was left unseen, which is why it appears that  Lawrence, Sue and Tony are preoccupied with things, but we never  discover what they truly are 