I am a Landlord that has a tenant in one of his properties. The Tenant wishes to buy the property. Does the Landlord need to pay the agency any comm(%) of the sale of the house. The agency only found the tenant and does not have a managed service. The agreement is within a Assured Shorthold Tenancy. I see no clause within the contract saying that i need to pay if the tenant buys the house within the contract period.

only if the agents terms and conditions with you say so - it wont be in the tenancy agreement.