Geospatial Modelling and Rights to Light - 13/01/2017

GW reports on last November’s RICS fascinating lecture by Andrew D. Thompson on how geomatics measurement techniques are being used in rights to light cases.

Ever since man first began to live in clusters of buildings with windows there must surely have begun a test of neighbourliness. Don’t build too near my property and don’t obscure my view, would have been an early test of relations. In today’s highly developed and complex world we have necessarily developed highly sophisticated software tools, legislation, tables and guides to solve these problems.

Andrew D. Thompson is a chartered surveyor who has specialised in this area. His talk was primarily to introduce the RICS’s latest guidance note Rights of light, 2nd edition, which came into effect on 1st July 2016. The guidance is the result of a working group comprising not only chartered surveyors from across the various professional groups but also lawyers and insurers.

Thompson began with a quote that echoes for our time: In London there were ‘bold speculators able to override the rights of the less wealthy’. It was said in 1865 when the capital was expanding rapidly. Plus ça change, as they say.


The new edition links the RICS Guidance in Measured Surveys of Land, Buildings and Utilities, 3rd Edition, 2014, which defines appropriate scales and accuracy for general survey tasks, to the sector’s specific needs of geospatial 3D rights of light models. Thompson drew attention to the growing use of laser scanners in this area.

Some developers are attracted to the quick adoption of off-the-shelf general model data captured via aerial survey techniques. By doing this, tolerance of accuracy is being lost. An aerial survey can have a tolerance of ± 500mm, which unless declared would be unknown to an end user of the data.

Thompson challenged the audience: can you tell the tolerance of a 3D model just by looking at the paper report? All you see are pretty computer images; all 3D models are not equal and the difference will now be found in the land survey data that was used to create the shape. The new guidance therefore has a specification table to help with the communication of the accuracy of the 3D model used in the report.


Driven by property values racing ahead of inflation, questions and disputes over rights to light are growing; the sums involved are substantial. Whilst there is legal case law precedent that provides structure for a settlement in the majority of disputes, the market is proving difficult in city centres. The commercial approach requires either a settlement based on development gain or an enhanced direct injury with both elements based on the court’s approach to the granting of compensation rather than an injunction.

The Corporation of London was required to step in and use the Planning Powers granted under the former section 237 of the Town & Country Planning Act 1990 to facilitate the development of 22 Bishopsgate, a 62-storey commercial skyscraper planned for construction in London which will stand 278m. This need for private sector developers undertaking major schemes to seek facilitation with local authority help is becoming more common.

The landscape changed on 13th July 2016 as section 203 of the Housing and Planning Act 2016 came into force replacing the former system. The new section 203 system has a much wider category of potential users. Known as the “specified authority”, this allows government departments and bodies with a statutory function, including undertakers such as utilities and nationalised companies like Network Rail to benefit from the powers. The potential source of a helpful partner to offer facilitation powers for major schemes is now wider than local authorities.

Whilst ransom risk is not over for small and medium schemes the logic of a proposed development being “too big” to be stopped by neighbours does seem to be driving the approach championed by the City of London.

Education and Qualification

In the past becoming a chartered surveyor required specific qualifications and experience; the wrong degree could exclude you from the profession. This view no longer reflects the needs of the current market. The RICS challenge has been to maintain the end quality of the final designation, whilst opening entry to all in the industry.

Achieving RICS qualification in specialist areas such as rights of light has historically been difficult, however the opening of the APC pathway now has created a route for graduate surveyors wishing to pursue an APC in any environmental area. Thompson explained that the APC now provides a more flexible route to qualification to practice. Even if you don’t hold a cognate degree the APC in combination with RICS Training has a route to qualification regardless of your start point so those working in rights of light can still achieve the designation, Chartered Environmental Surveyor.

Recent APC success story is Gilsen Osman MRICS, Daylight and Sunlight Manager of BLDA Consultancy. Her work in planning, sustainability, natural light and supporting developers in the design phase provided the necessary experience necessary to achieve first AssocRICS and then full MRICS.

Whilst the end experience level required to achieve MRICS has not been lowered, the route to achieve that point is now wide and inclusive. Therefore any capable graduate working in environmental design areas such as rights of light should look again.

This article was published in Geomatics World January/February 2017

Last updated: 08/07/2020