When a tenant exercises a break right in a lease it must usually ensure that it serves the notice on its landlord, at the correct address, in the correct form, by the correct method of service and in compliance with any preconditions.

However, the right of a landlord to question the validity of a notice may be waived by acceptance of the incorrect document by the landlord or its agents.

In a recent case, MW Trustees Ltd and Ors v Telular Corporation, any break notice had to be served by special delivery or by hand on the landlord. The tenant served the notice by special delivery on the former landlord. The former landlord, realising the tenant's error, informed the tenant of the identity of the current landlord. The tenant then emailed a copy of the notice to the current landlord's agent. The agent responded, “we accept the attached letter and can confirm we are happy for you to break the lease, however please could you readdress this letter to the following address...”

The court held that the agent's response meant that the break had been accepted even though the notice had not been correctly served. If the agent had not responded, the landlord would have been able to prove that the notice was invalid. Landlords (and their agents) should be extremely wary because an "in principle" acceptance could be interpreted as unconditional acceptance.