Termination Clause in Consulting Contract

[jamescook783]

An individual consultant has entered a freelance service contract with a subcontractor to implement a project. The termination clause involves the contractual authority. It reads ""Each party may terminate this Agreement at any time on not less than 30 (thirty) days prior written notice to the other party, subject to the Contracting Authority giving its prior written consent in the case of termination by the Consultant." The consultant wishes to terminate the contract and feels that the condition of third party consent is against common decency.

Is this a valid clause or can the right of the third party be challenged under British law?