I'm not an expert on legal matters but several things about this problem make me ask:
1. Trespass is defined as "make unlawful or unwarrantable intrusion" in my dictionary. I fail to see how fulfilling one's obligation by having an escape route to comply with legislation could fall into either catagory; the requirement for an escape route is lawful and not unwarrented, surely.
2. I presume the landlord has control over the buildings and therefore is obliged under the RR(FS)O to co-operate with the tenants to let them meet their obligations?
3. Don't the leases have anything to say about access/egress from the premises?
1. In my case it was clearly unlawful intrusion as a Court had issued an Order prohibiting access, the fact that it was an escape route is not the landowners problem. He gave plenty of notice, 6 years infact that he didn't want the shop to use his land as an escape route and had eventually had to seek a Court Order to prohibit access, he gave plenty of notice of his intention to block the exit.
The employer could easily have provided an alternative escape route in this case but chose not to.
2. The duty to co-operate and co-ordinate is only applicable where two responsible persons, share or have duties. If you chose to make use of my back passage without my consent I surely don't share or have duties towards you, and my back passage is very dear to me!!
3. Leases would surely only bind the parties that signed up to them, a common problem with wayleave agreements.