Representation:-
an employer who finds himself liable for an injury suffered by an employee working on a 3rd party's site may be able to claim a contribution from the 3rd party, pursuant to the duty of care imposed by the Occupiers' Liability Act 1957 and/or (for example) by the Construction (Health, Safety and Welfare) Regulations 1996, SI 1996/1592. However this will depend on whether it would be fair and reasonable in all the circumstances to expect the 3rd party to be liable.
For relevant general notes see Health and Safety at work/civil liability .