On 22 September 2021, HS2 (the interested party) made an application under Sch.17 of the 2017 Act for approval of details in the form of plans and specifications relating to engineering works. These were contended to be within the works authorised by the 2017 Act. Under S.20 of the 2017 Act, deemed planning permission is granted for the carrying out of development authorised by the Act, including development authorised but which does not consist in the carrying out of a work which is within the definition of scheduled works. Schedule 17 imposes conditions on development under the act with the benefit of deemed planning permission.

On 8 October 2021, the claimant (Warwickshire Borough Council) declined to determine HS2 Ltd.’s application on the basis that the proposed works were not authorised under the 2017 Act, and did not have the benefit of deemed planning permission. An appeal hearing against the non-determination took place before an inspector on 27 April 2022, at which point the defendants (Secretaries of State) directed that they would jointly determine the appeal.

On 14 May 2024, the Secretaries of State reached their decision, where they disagreed with the inspector’s original conclusions and recommendation. Conversely, they concluded that section 2(1)(i) is sufficiently broad to cover an extension to a tunnel, and ancillary works to such an extended tunnel. Contrary to the inspector's conclusion, the Secretaries of State considered that the BTEP is authorised under the HS2 Act, and thus the BTE and relocation of BTEP benefits from deemed planning permission under the HS2 Act.