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Nettlebed Estate

B Road with mature trees on made-up ground

The strong winds of Storm Eleanor have prompted us to share a case study of an estate that Lockhart Garratt Ltd (LGL) are assisting with meeting their duty of care obligations. In particular, this is in regards to risks associated with trees.

Landowners have a statutory duty of care  under the Health and Safety at Work Act 1974 and Occupiers Liability Act 1984, to do all that is reasonably practical to ensure that people are not exposed to a risk to their health and safety from trees in their ownership.  This duty can be fulfilled by having a system of inspections in place to help control the risk from trees.


Site Information and Brief

Nettlebed Estate is a large estate located in southeast Oxfordshire. The majority of the Estate consists of woodlands and agricultural land and the Estate also owns a number of tenanted properties. Large areas of mature broadleaf woodland are separated by busy roads and the majority of properties have mature trees within their curtilage.

LGL was engaged to provide expert advice and guidance in relation to the management of tree related risks within the Estate ownership.


LG’s Approach/Involvement

Surveying roadside trees

The forestry team at LGL have been working with Nettlebed Estate since 2011.  We were able to utilise their knowledge and experience of the Estate, in conjunction with advice from the owners, to determine the best possible approach to tree risk management.

Based on these discussions, in 2015 we undertook a baseline survey, following guidance provided by industry best practice and principles including the National Tree Safety Group ‘Common Sense Risk Management of Trees’[1], and HSE guidance ‘HSE SIM 01-2007-05 – Management of the risk from falling trees[2]. This consisted of a walkover survey of all trees within falling distance of designated targets:

  • Roads;
  • Access tracks/drives; and
  • Property.


Snow damaged roadside tree

The survey was undertaken using Visual Tree Assessment (VTA) techniques and aspects of the International Society of Arboriculture’s Tree Risk Assessment Qualification (TRAQ) methodologies. Following the guidance provide by Common Sense Risk Management of Trees (with which LGL has been involved with since its inception), a negative survey was determined the most appropriate method of surveying trees. This meant that while every tree that was within falling distance of the designated targets was inspected; only those trees with actionable defects were recorded. This reduces the length of time it takes to undertake the survey as well as cost to the Estate.


On completion of the baseline survey, we worked with the resident land agent and the Estate owners to develop and implement a Tree Risk Management Policy (TRMP). This document clearly sets out an approach to tree risk management and provides a clear auditable trail of all actions taken to minimise the risks associated with trees.

The TRMP includes creating a zoning plan. This plan provides an overview of the land owned by the Estate and considers the rate of occupancy and usage of all parts of the Estate.  The zoning plan provides three categories of use/occupancy; high, medium and low. Arising from the zoning exercise, we were able to help the Estate establish the frequency with which inspections should take place, and determine the qualifications and competencies for who should be doing the inspection.  The development of this approach has resulted in a re-inspection schedule that is cost effective, reasonable and practical for the Estate to adopt and enables a proactive approach to tree risk management.

Fungal fruiting bodies at base of roadside tree

The findings of the arboricultural survey were also summarised in an arboricultural report. This report included:

  • a detailed tree schedule that contained the information collected during the survey;
  • a risk rating for the recorded trees; and
  • recommended works and timeframe for completion of works.

This document has enabled the instruction of arboricultural contractors to complete the recommended works within the designated timeframes to address the identified hazards. We have assisted with the sourcing of quotes from contractors and monitoring completion of works.

We are still involved in providing expert support on matters relating to tree risk within the Estate and recently undertook a re-inspection of all trees within the zone with the highest levels of occupancy/use, in accordance with the re-inspection scheduled detailed in the adopted TRMP.

The TRMP also required the Estate to undertake informal reviews of roadside trees following extreme weather events.   Following the heavy snow and high winds at the end of 2017, we carried out a drive-by survey of those designated areas. This is a cost effective method for assessing large populations of trees and identified areas requiring further assessment. It also allowed targeted and urgent tree works to rectify storm damage to be undertaken quickly.



Nettlebed Estate has adopted a pragmatic and bespoke Tree Risk Management Policy that defines its approach to tree risk management. This includes zoning the site in accordance with rates of occupancy, determining the frequency of the inspection regime, considering the qualifications and competencies of those undertaking inspections and details the responsibilities of those involved in the management of tree related risk. This document has enabled the Estate to adopt a cost effective and reasonable approach to managing trees under its control to ensure that a proactive and defensible system is in place.


LGL Services Provided


  • Baseline tree hazard survey;
  • Professional advice;
  • Liaison with Highways Authority and Local Planning Authority;
  • Tree Risk Management report (including Tree Location Plan);
  • Tree Risk Management Policy (including Zoning Plans); and
  • Ongoing professional advice and input into tree related matters.


  • Preparation of long-term silvicultural plans;
  • Securing  woodland grant funding;
  • Contract management; and
  • Timber sales.



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