Measurements of exceptional trees have been recorded for a considerable number of years: initially out of curiosity, especially about maximum size, and then to investigate the potential for growth and productivity according to species and situation. The Forestry Commission tree register provided all the measurements for early editions of this title. The register was begun in 1952 as a survey to locate trees of outstanding size, vigour and quality for use as prospective material for plantation tree breeding experiments. Very large ancient, ornamental and obscure specimens were added to the register after 1954. Historical information, particularly from the beginning of the 20th century, was subsequently researched, and extant trees were located and remeasured. This work continues today, supplemented increasingly since 1985 with routine tree measurements recorded by The Tree Register of the British Isles which is a charitable trust. This publication is still available to order in hardcopy.