Recorded in a number of spellings including Cansdale, Cansdall, Cansdell and Cansdill, this seems to be an English locational surname. Unfortunately no such place as Cansdale or indeed anything quite like it in spelling appears to be recorded in any of the known gazetters of the British Isles. The prefix 'can' is an Olde British and Welsh pre 7th century word which means valley, and it would seem that the suffix of either the Anglo-Saxon or possibly Danish-Viking 'dael' or the English 'dell' meaning hollow has been grafted onto it at a later date to give 'valley-valley'. This is unusual but not quite unique. Pendle Hill in Lancashire is made up of three elements all of whom translate as hill! It may seem strange that a complete valley can 'disappear', but then some five thousand medieval sites are known to have vanished over the past thousand years or so, with usually the only public reminder in the 20th century being a surviving surname. To add to the confusion, often as with this one, they are in several spellings, any one or none, of whom, could be the original form. Examples of the surname recordings taken from surviving church registers of the diocese of Greater London include: Elizabeth Cansdill, who married William Bull at Christ Church, Spitalfields, on July 10th 1797, and William and Mary Cansdale, who were witnesses at the same church on April 15th 1822.