NEGLIGENCE - breach of statutory duty - whether duty rests on persons "actually carrying out building work" or also on head contractor.; NEGLIGENCE - duty of care - scope of duty - whether head contractor liable under general duty of care to subcontractors - whether head contractor under non-delegable duty to provide safe system of work.; NEGLIGENCE - occupier's liability - principles to be applied.; BUILDING AND CONSTRUCTION - subcontractors - whether employee or subcontractor.; CONTRACT - implied terms.; LIMITATION OF ACTIONS - commencement of limitation period - application for extension refused - when time begins to run - whether solicitors failed to sue relevant party in time. ; LIMITATION OF ACTIONS - applicability of principle enunciated by Deane J in Hawkins v Clayton - [1999] NSWSC 443 - NSWSC 1999 case summary — Zoe