Employers are responsible for the health and safety of their employees, the employees of others working on their premises, and members of the public who may be affected by their activities. This could include visitors to their premises, local residents, customers, and even trespassers.
Section 3 of the Health and Safety at Work Act 1974 requires employers not to expose non-employees to risks to their health and safety. Section 4 of the HSWA puts a similar duty on the controller of the premises, which may well be, but not necessarily, the employer.
Under the Occupiers' Liability Act 1957 and the Occupiers' Liability Act 1984, occupiers must take reasonable care of the safety of visitors to their premises.
This duty of care extends to unlawful visitors, such as trespassers, if the occupier: