8.1 When the Authority has confirmed the Estimate in accordance with paragraph 7.1 of this Section 3, Sub-hubco shall, subject to Sub-hubco obtaining all new or amended Necessary Consents that are required and have not already been obtained, implement the required Medium Value Change in accordance with the Estimate. Where an extension of time has been agreed as part of the Estimate the Completion Date [relevant Phase Completion Dates] shall be extended as agreed in the Estimate.

8.2 Sub-hubco shall notify the Authority when it considers that the Medium Value Change has been completed.

8.3 If:

8.3.1 Sub-hubco fails to provide a response pursuant to paragraph 2.2 of this Section 3 within fifteen (15) Business Days of the date of the Medium Value Change Notice; or

8.3.2 Sub-hubco fails to provide an Estimate in accordance with paragraph 3 of this Section 3; or

8.3.3 the Authority has confirmed an Estimate but Sub-hubco fails to fully implement the Medium Value Change within [ten (10)] Business Days after the expiry of the time for implementing the Medium Value Change set out in the Estimate Low Value Change (as such time may be extended for any delay that is, or is equivalent to, a Delay Event);

then, subject to paragraph 14.3 of this Section 3, the Authority may notify Sub-hubco that the Medium Value Change Notice is withdrawn and, following such notification, may procure the implementation of the Medium Value Change without further recourse to Sub-hubco, but the Authority must ensure that the Medium Value Change is carried out in accordance with Good Industry Practice and to the standards that would have applied to Sub-hubco if it had implemented the Medium Value Change.