I will disagree on which lease might be valid. But I agree we would have to see both to tell for sure. He said there was an original lease that includes that provision that was signed and the landlord has a copy that he has seen and that is what the landlord is going by. It seems like neither side has a copy of a current (2nd/later) lease that was possibly signed by either side after the term of the original lease. It is very possible a new lease was written but never signed so the old provisions in the old lease would apply.... It is possible the prior tenant believed himself to be under the new lease but didn't protect himself by signing it. In the end, the takeover tenant should have gotten a signed copy of the updated lease when he tookover. He assumed a non-signed lease was in affect and that a vague letter would suffice. Unless his letter specifically detailed the lease provisions and possibly the updated lease date.

He stated above that he wrote and the landlord accepted a continuation of the current situation, but what is unclear is what both thought the current situation was since a new lease was not negotiated or signed at that point, rather he tookover the "current" one. If he can't come up with an updated signed lease from the prior tenant that states the new provisions (and not something that he signs now rather than back at negotiation time), then I don't see where the 2nd can now be validated and signed nor count as the updated lease. But again I agree that the leases and other written communications could flip my perspective. The devil is going to be in the details.