Barrell Tree Consultancy (BTC) advises on trees in the legal and planning sectors. Since concentrating solely on consultancy in 1995, it has developed from being a sole trader to one of the most successful arboricultural consultancies in the UK. At the same time, it has developed an international reputation for designing and exporting tree assessment methods. Vital in BTC’s success has been its network, running into thousands of contacts built up through decades of satisfied clients, and staff handpicked for their calm temperament and ability to solve clients’ problems. A glance at the BTC website reveals the diversity of its client base. Projects range from the Bomber Command Memorial at Hyde Park Corner and public realm refurbishment in Mayfair to the retention of mature trees in London’s Leicester Square, installation of tree houses at the five-star Chewton Glen Hotel in the New Forest and construction of a new Mix Stage beneath protected mature trees at Abbey Road Studios. Project delivery at the highest level requires decades of experience. All seven of BTC’s consultants are extree officers. They know planning inside out and have a practical climbing background. All seven are Institute of Chartered Foresters chartered arboriculturists and six are Arboricultural Association registered consultants — the top consultancy credential in the UK. Staff retention is vital. Founder and managing director Jeremy Barrell aims to “employ for life”, investing in training to peak performance, matching salaries within the market and offering employment packages that go beyond the conventional. Consultants are encouraged to attend and speak at international conferences and take leading roles in professional initiatives. The business is known for its innovation in tree assessment. During the 1980s, it developed a method of assessing trees on development sites called Safe Useful Life Expectancy, which evolved into the international TreeAZ method. In 2008, BTC began the development of a heritage tree assessment method called TreeAH, which is now forming the basis of a project to establish an international heritage tree register. BTC shares what it learns, publishing its tree assessment methods free of charge for all to use. It also produces articles and papers each year to promote its ideas at the cutting edge of arboricultural thinking.