For 70 years I have worked in the Herbarium at Cambridge University on the British and European floras. I have collected, often with Gina's company, about 30,000 numbers consisting of some 50,000 specimens from most parts of the British Isles and made many visits to Continental Europe. Particular attention has been given to most critical genera: Cerastium, Chenopodium, Conyza, Crepis, Dactylorhiza, Euphrasia, Fumaria, Hieracium, Limonium, Polygonum, Pilosella, Prunus, Rhinanthus, Rumex, Salicornia, Salix, Scleranthus, Sorbus and Ulmus. In helping friends in various ways I have also considered the taxonomy of Alchemilla, Ranunculus subgenus Batrachium, Potamogeton, Rubus and Taraxacum. I have also spent much time studying ecotypic and geographical variation, in particular comparing those variants which occur on the coasts in dunes, shingle and saltmarsh with those growing as arable weeds and with those in mountains. Special attention has also been given to trees and shrubs.

It had long been my wish to publish this information in a critical flora of Great Britain and Ireland. In the 1970s a group of us tried to get a grant to carry this out, but we were unsuccessful. Clive Stace then started work on his New Flora of the British Isles, which was first published in 1991, with a second edition in 1997 and a third in 2010. In it he gives only short descriptions and omits most of the species in the large apomictic genera and many of the infraspecific variants whose differences are not apparent in his abbreviated diagnoses. Numerous introduced species are included by Stace in a British and Irish flora for the first time, detailed descriptions and specimens of many of which have previously been difficult to find. Stace's flora is to my mind an excellent field guide, which it would be difficult to better, but it does not give the detailed descriptions that are needed to confirm the identification of a plant which is new to you. A good description in my opinion is one in which a picture of the plant unfolds before you as you read it and includes as much of the variation as possible.