Recorded in several spelling forms including Trenbay, Trenbey, Trinbey, Trineby, Trenbee and Trunby, this is an English locational surname. It is at least half Viking, the ending being formerly 'bi', the pre 8th century Scandanavian word for a farm, and still found in the English word 'byre'. The prefix is much more difficult. There does not seem to be any existing place in the isles of Britain of any similar spelling, and therefore it has to be assumed that this is a 'lost' medieval village or even a single farm name. Some five thousand British surnames probably originate from now 'lost' places, of which the only reminder in the 20th century, is the surname, often, as with this one, in many varied forms. As to which spelling is the correct one, or indeed if any are, is a matter of conjecture. It is quite likely that the village was in East Anglia as this was the area which was the longest occupied by the Danes, and where they have left their greatest memory in the place names ending 'by'. It is possible that this name originally commenced 'Trent', the name of the river which flows through part of the Anglian region. The Trent also has a habit of changing its course, which may also explain why 'Trent-by' no longer exists. Examples of the name recording include Magdalen Trenbee, christened at church known as St Sepulchre, in the city of London, on September 22nd 1680, Thomas Trunby christened at St Ann's Blackfriars, on July 14th 1752, and William and Ann Trinbey, witnesses at the famous church of St Mary-le-Bone, Marylebone, on August 19th 1857.