The original AST agreement started on 1st February 1999 and finished on 31st January 2000. The same tenants have remained in the property at the same rent of £500 pcm on a periodic. The landlord has not put the rent up because the property requires a lot of work and she does not want to spend the money, and the tenants have been happy with this arrangement. Another agent will be taking over the management and have questioned the periodic tenancy. They claim that it cannot continue beyond three years! I have always understood that a periodic can go on as long as everyone is in agreement.