Can local authority insist on an extension to the applicant's S.42 consultation? The 5 April consultation deadline does not allow the council enough time to take their response through the authority's committee cycle and make any subsequent amendments afterwards.

As long as the applicant is providing at least the statutorily prescribed minimum period of 28 days from the day following the receipt of the S.42 consultation documents, there is no obligation on the applicant to extend the consultation period in view of committee cycles. As indicated in IPC Advice Note 1 on Local Impact Reports: "Local authorities should ensure any necessary internal authorisation processes are in place to meet the timetable. It is entirely a matter for local authorities to determine whether or not an LIR requires approval by Members and in what form."
The same principle applies to local authorities' other contributions to the NSIP process. For example at acceptance stage local authorities typically have around 10 working days to respond to the IPC on the applicant's consultation report advising on its adequacy.