Light Obstruction Notices

A Light Obstruction Notice (LON) is a powerful legal tool that can prevent neighbouring properties from acquiring a right to light, which could otherwise delay or derail your project.

Anstey Horne are the UK’s leading specialists in rights of light, helping developers across England and Wales mitigate risk and preserve their development potential.

What is a Light Obstruction Notice?

Under the Rights of Light Act 1959, a Light Obstruction Notice creates a notional (legal) screen across your boundary.

This hypothetical obstruction is registered as a local land charge against neighbouring land and interrupts the 20-year period required to gain a legal right to light under the Prescription Act 1832.

No physical barrier is needed – the law treats the notice “as if” an obstruction exists.
If no objection is raised within 12 months, the prescriptive clock is reset to zero.
This allows developers to avoid costly delays, design compromises, or compensation claims.

When Should You Consider Serving a Light Obstruction Notice?

Light Obstruction Notices are most effective when used proactively.

If a neighbouring window has had unobstructed daylight for nearly 20 years, the owner may be on the brink of acquiring a legal right. Serving LONs before the 20-year mark can:

Prevent the acquisition of new rights of light
Secure long-term development potential – even if construction isn’t imminent
Identify existing claims early through statutory neighbour notifications
Avoid expensive litigation or redesigns during planning or construction phases

Best practice: Begin assessing potential rights of light issues once adjacent buildings are approaching 18 years of uninterrupted light.

Processing Light Obstruction Notices

We handle the entire process of serving Light Obstruction Notices and diligently monitor them throughout the period required for them to take effect, which can extend beyond one year.

In addition, we maintain close collaborations with law firms that specialize in this niche area of property development.

Should you require legal advice or representation, we can recommend experienced legal advisors who can assist you in navigating these complex matters seamlessly.

Our Light Obstruction Notice Services

At Anstey Horne, we provide a comprehensive end-to-end Light Obstruction Notice service, including:

Rights of Light Assessment

Analysis of neighbouring apertures and potential risk
Determination of when and whether prescriptive rights may arise

Strategic Advice

Feasibility studies on whether a LON is the most appropriate tool
Coordination with your wider legal or development team

Legal Process Management

Preparation and submission of applications to the Upper Tribunal (Lands Chamber)
Notification of all affected parties and interested landowners
Local registration of the LON as a <strong>land charge</strong>
Monitoring throughout the one-year notice period

Legal Collaboration

Referrals to trusted rights of light solicitors when legal action or defence is required
Integration with negotiation, design strategy or insurance solutions

Strategic Management of Rights

A single unchallenged window could cost your project months of delay or six-figure compensation. By serving a Light Obstruction Notice, you take control of the legal position before problems arise.

With offices in London, Birmingham, Bristol, Cardiff, Leeds, Manchester, Norwich & Plymouth we provide advice on LONs on sites all around the UK.

For more information on Light Obstruction Notices, how a right to light is acquired, measured and defended, please also see our Fact Sheet.

The Land Tribunal's explanatory note on LONs can be found here.