The UK Government's Planning and Infrastructure Act 2025 removed statutory consultation requirements for Nationally Significant Infrastructure Projects (NSIPs) in England, citing concerns that the process hitherto had created a "doom loop" of endless consultation that delayed projects without improving outcomes for either projects or host communities. Critics of the Government have claimed that this move will just reduce democratic oversight and public voice in planning. There is, however, a paucity of empirical evidence about what constitutes meaningful consultation in NSIPs and for whom.

Addressing this gap, this paper reports the findings of a mixed methods study of consultation practice focussed on the experiences of both project applicants and consultees across multiple NSIPs, providing insight into what works, for whom, and with what outcomes.

Key findings point to the lack of shared understanding of the purpose of consultation, with applicants framing consultation in instrumental terms while consultees place greater emphasis on influence and fairness. This divergence in expectations is a consistent source of tension. The findings also point to critical success factors such as establishing clarity early about what can genuinely be influenced versus predetermined requirements; optimal timing and sequencing of consultation before positions become entrenched; and the value of recognising both tangible and intangible outcomes from consultation and engagement activities.

More broadly, these findings have implications for how the longstanding principle of public participation in planning is mediated within projects deemed to be in the national interest, where centralised decision-making frameworks intersect with expectations for localised democratic engagement.