After reading it. I bet there was no snake.
The agent took no action after being told by the tenant that his friend heard a snake in the wall. SO the tenant just packed up his bags and left. If I was the tenant and confident my friend did actually hear a snake I'd possibly leave as well. But it was the tenants fault for not contacting tribunal before leaving and taking appropriate steps.
Its a tough one, If I was the agent I'd probably get this in writing from the tenant (that there is a snake). Also in writing that the tenant agrees that if there is nothing in the wall the tenant must pay for the snake catcher's invoice.
Thanks for that. Very interesting read.