We are a company that operates within the boundaries of another company (use to be same, but now sold off part of business). We rent the premises from the landlord company. Hyperthetical situation: Premises owner send in maintenance (Contractors) to change lighting strips. What requirements are there on us to ensure that there are safe systems of work in place? and if an accident happened, could we be prosecuted for not controlling the work and risk?

Would it not also be important to ensure that your operations are not something that might cause a hazard? Perhaps trip hazards, fumes, or even noise.

It's got to be about cooperation hasn't it?

Your landlord tells you - "I'm sending in contractors to change the strip lighting in your unit."

You reply - "Fine but could you get them to send a representative around first so we can ensure there are no H&S issues."

Should an accident occur after this I think you would at least have a defence as you have shown that you have made the effort.

But I'm not a legal chap

also responsibility of the landlord to ensure the contractors visit the site for risk assessment where this is needed and to liaise with thos eon the site - in this case yourselves and the other party.