Foreign and Commonwealth Office (FCO) treaty records, which began in 1835, list 6,826 bilateral and multilateral treaties to which the United Kingdom became party and which entered into force for the United Kingdom. The authoritative “Index of British Treaties”, published by HM Stationery Office in 1970, contains 1,498 such treaties for the period 1101 to 1835, thus giving a total of 8,324 treaties to-date.
This figure relates to treaties that have not been expressly terminated or otherwise recorded as no longer in force for the United Kingdom. FCO treaty records are held in electronic format and comprise both modern elements and information derived from 19th century records. The number of treaties stated above is the most accurate figure possible based on the finding-aids available.