The London Stones were placed to mark the boundaries of the jurisdiction of the City of London over the River Thames and part of the River Medway from the 12th century to the mid-19th century.

In 2014 the London Stones were the subject of an archaeological report (1) by English Heritage following the wider Hoo Peninsula Historic Landscape Project. The stone was one of three earliest surviving stones thought to date to the 18th century that were originally located at Staines, Southend-on-Sea and Upnor.

The following text is from the original listed building designation:
FRINDSBURY EXTRA CP LOWER UPNOR TQ 77 SE 6/7 Boundary stone, ('The London Stone') - II
Boundary stone. Probably C18. Stone 4 feet high, square, with pyramidal top. Marked '1204/God preserve the City of London'. Referred to as the London Stone on O.S. Maps.
Listing NGR: TQ7441370871

English Heritage, List of Buildings of Special Architectural or Historic Interest (Map). SKE16160.

<1> English Heritage, 2014, The London Stones: Marking the City of London's Jurisdiction over the Thames and Medway (Bibliographic reference). SKE31435.