City of London Coat-of-Arms - Billingsgate Market, Aspen Way, London, UK - Coats of Arms on Waymarking.com

The Heraldry of the World website tells us about the City of London coat-of-arms:

Official blazon:
Arms: Argent a Cross Gules in the first quarter a Sword in pale point upwards of the last.
Crest: On a Wreath of the Colours a Dragon's sinister Wing Argent charged on the underside with a Cross throughout Gules.
Supporters: On either side a Dragon Argent charged on the undersides of the wings with a Cross throughout Gules.
Motto: 'DOMINE DIRIGE NOS' - Lord, direct us.

Origin/meaning:
The arms of London have never officially been granted, but have been recorded at the College of Arms, albeit without supporters and crest. The crest and helmet were granted on April 30, 1957.

The shield combines the cross of St. George with the emblem of the city's patron, St. Paul. The first cathedral dedicated to St. Paul was built in 605 in the city. The patron saint itself already appears on a 13th century seal. The arms appear for the first time on a seal from 1380.The sword has often been described or attributed to the dagger with which Sir William Walworth, Mayor of London, stabbed the rebel Wat Tyler on June 15th, 1381. The arms with the sword, however, predate this event. Another story states that the sword was granted by King Richard II as a reward for William Walworth's services to the King. There are, however, no historical evidences for either story. The dragons appear for the first time on an illustration in a book from 1633. The same book, the Survey of London, by Stow, also first mentions the motto 'Domine dirige nos' (Lord, direct us).

On a seal of the Mayoralty dating from the late 14th century the arms show two lion supporters. These are not seen elsewhere.
The origin of the dragons is not clear, it may be that they are derived from the story of St. George, the patron saint of England, in which the saint kills a dragon. The sword and the dragons thus distinguished the arms of the city from those of England.

The oldest known image of a crest dates from 1539 when they appear on the reverse of the common seal of the city. The oldest image is not very clear and looks like a fan-like object, charged with the cross of St. George. By the end of the 17th century, the crest has developed into the dragon wing. Sometimes the arms were shown with two wings, facing each other.

The City of London website has a brief history about Billingsgate Market that advises:

The Market rights of the City of London were based on a charter granted by Edward III in 1327 which prohibited the setting up of rival markets within 6.6 miles of the City, (six and two thirds miles being the distance a person could be expected to walk to market, sell his produce and return in a day). In 1400 King Henry IV granted to the citizens the right, by charter, to collect tolls and customs at Billingsgate, Cheap and Smithfield. Since then, the Billingsgate Market Acts of 1846 and 1871 and the City of London (Various Powers) Acts of 1973, 1979, 1987 and 1990, have confirmed the City's role as the Market Authority and laid down its responsibilities and rights, including the making of regulations, the collection of tolls, rents and other charges.

Billingsgate was known as Blynesgate and Byllynsgate before the name settled into its present form. The origin of the name is unclear and could refer to a watergate at the south side of the City where goods were landed - perhaps owned by a man named 'Biling' - or it may have originated with Belin (400BC) an ancient King of the period.

Billingsgate was originally a general market for corn, coal, iron, wine, salt, pottery, fish and miscellaneous goods and does not seem to have become associated exclusively with the fish trade until the sixteenth century.

In 1699 an Act of Parliament was passed making it "a free and open market for all sorts of fish whatsoever". The only exception to this was the sale of eels which was restricted to Dutch fishermen whose boats were moored in the Thames. This was because they had helped feed the people of London during the Great Fire.

Until the mid-nineteenth century, fish and seafood were sold from stalls and sheds around the 'hythe' or dock at Billingsgate. As the amount of fish handled increased, a purpose-built market became essential. In 1850 the first Billingsgate Market building was constructed on Lower Thames Street but it proved to be inadequate and was demolished in 1873 to make way for the building which still stands in Lower Thames Street today. This was designed by the City Architect, Sir Horace Jones, and built by John Mowlem. It was opened in 1876 and is now a listed building.  In 1982 the Market relocated to Docklands.??