You can report suspected unauthorised development to the planning enforcement section of the relevant local authority, usually by phone, email, or an online complaint form, ideally with the address and a description of the works. The council will assess whether to investigate; a complaint does not guarantee that enforcement action will follow.
Complaints about suspected unauthorised development are made to the planning enforcement section of the local authority in whose area the property is located, most commonly by phone, email, or an online enforcement complaint form available on the council's website. Some authorities allow anonymous complaints, though providing your name and contact details can help if the authority needs to follow up for clarification, and your identity is generally kept confidential from the person being investigated.
A useful complaint includes the exact address or a clear description of the location, details of the works or use suspected of being unauthorised, dates if known, and any supporting photographs. The local authority is not obliged to act on every complaint automatically; it will use its judgement to decide whether an investigation is warranted, and complaints considered trivial, unclear, or outside the planning system's remit (such as boundary disputes not involving development) may not lead to formal action.
Once a complaint is logged, a planning enforcement officer may inspect the site, review the planning history, and where appropriate issue a warning letter to the property owner. The complainant does not usually receive detailed updates on the outcome, since enforcement correspondence is generally between the authority and the property owner, though basic status information can sometimes be obtained through a follow-up query or a request under the Freedom of Information framework.