I read with interest your advice given on April 12, 2017 regarding access rights. I understand there are two pieces of legislation that could be used:
s53 of the Planning Act 2008
s172 of the Housing and Planning Act 2016
To paraphrase, your advice was to use s53 of the Planning Act 2008. This states:
"Any person duly authorised in writing by the Secretary of State may at any reasonable time enter any land for the purpose of surveying and taking levels ..."
Please could you comment on the following:
1 - if access has been granted under s172 of the Housing and Planning Act 2016, ie against your advice, will the findings be considered acceptable in the DCO
2 - if access is being requested under s172 of the Housing and Planning Act 2016, what should the land owner do?
3 - if access is requested under s53 of the Planning Act 2008, what evidence does the requester have to provide to demonstrate that they are "authorised in writing by the Secretary of State"

1 - The Planning Inspectorate is not responsible for requests made under s172 of the Housing and Planning Act 2016. Decisions regarding whether or not to accept applications for examination are made in accordance with the requirements of the Planning Act 2008 and associated statutory instruments.
2 – The Planning Inspectorate is not responsible for requests made under s172 of the Housing and Planning Act 2016. As such the Inspectorate is unable to provide advice regarding this process.
3 – If the Secretary of State authorises access to land under s53 of the Planning Act 2008, it will issue an authorisation notice to the requester. The authorisation notice would also be published on the Planning Inspectorate website. Further information is available in Planning Inspectorate Advice Note Five: Section 53 – Rights of entry.