Today London Stone consists of a block of Clipsham limestone about 21 inches (53cm) wide, 17 inches (43cm) high and 12 inches (30cm) front to back. This is all that is left of what was originally a very large stone block set upright in the roadway, on the south side of the road nearly opposite where it is now. By the time of the Great Fire, the Stone was already badly worn and damaged. In 1742 what was left of it was regarded as a traffic hazard and it was moved and placed against the wall of St Swithin’s Church on the north of the road, where an office block stands today.
Much discussion has gone on over the centuries as to the origin of London Stone. It may have originated in the Roman period and been part of the front entrance to a large public administrative building on the waterfront. The suggestion has been made that it was the central milestone, from which all others were measured in the province. Another suggestion is that it may have been an Anglo-Saxon wayside marker or cross but there is no evidence for this.
It was first mentioned by name in a document dated about 1100. In the medieval period it was regarded as the very heart of the City of London. It was a venerated antiquity but its original purpose was already forgotten by the 12th century when it was called ‘Londenstane’. In 1450 the Kentish rebel Jack Cade entered London with his followers and struck his sword on London Stone, claiming to be ‘Lord of London’.
In the 16th century, William Camden believed that it was the central Roman milestone while, in the 17th century, Christopher Wren saw foundations below it during rebuilding after the Great Fire and was convinced it was not a mere pillar but something more elaborate and connected with a Roman building seen to the south.
Most of the stories about the importance and significance of London Stone are recent inventions and it is not known when or why the Stone was erected. For example, there is a saying ‘So long as the Stone of Brutus is safe, so long will London flourish’. This is not a medieval proverb or an ancient tradition as it was invented in 1862.