Guuilden Gonn in Houndsditch

Brass Ordnance cast in Houndsditch by the Owens. About the latter end of the Reign of King Hen. 8. three Brethren that were Gun Founders, sirnamed Owens, gat Ground there to build upon, and to enclose for casting of brass Ordnance. These occupied a good Part of the Street on the Field side, and in short time divers others also builded there; so that the poor bedrid People were worn out, and in place of their homely Cottages, such Houses builded as do rather want Room than Rent. [Which Houses be for the most part possessed by Brokers, Sellers of old Apparel, and such like.] The Residue of the Field was for the most part made into a Garden, by a Gardiner named Cawsway, one that served the Markets with Herbs and Roots. And in the last Year of King Edward VI. the same was parcelled into Gardens, wherein are now many fair Houses of Pleasure builded.

Owens' Gunfoundry in Houndsditch. The foundry was afterwards commemorated by Gun Yard on its site (later called Gun Square).

From Gun Culture in Early Modern England (U Virginia Press, 2016), by Lois G. Schwoerer:

Henry [VIII]'s government also forwarded the careers of English gunfounders. Two brothers, John and Robert Owen, whom Baude [Peter, a French gunfounder working as a gunner in the Tower] had trained in gunfounding, located in the Houndsditch area sometime before 1531. John Stow reported that the brothers "gate ground there to build upon, and to inclose for the casting of Brasse." He maintained that John Owen was the first Englishman to make brass ordnance. The Owens' work won Henry's approval, and in 1537 he gave the brothers a pension of 8 pence a day and in 1540, on the eve of the war with France, the "Bellfounders house." Thanks to the government, they prospered. One brother became prominent enough for his death on 6 July 1553 to be noticed by the diarist Henry Machyn. The Owens' children, continuing in their fathers' fooststeps, also succeeded. In 1589, their foundry business was identified by the "Signe of the Guuilden Gonn in Houndsditch," and their house was known by a similar sign. They became "unto the Dayes of King James most ready exquisite Gunmakers." The critical factor in the success of these men was the assistance of the government.

From The Gun-Founders of England: With a List of English and Continental Gun-Founders from the XIV to the XIX Centuries, by Charles Ffoulkes (Cambridge UP, 1937, rpt. 2011):

In 1531 the brothers John and Robert Owen appear in the State Papers as gunfounders and their occupation of a site at Houndsditch is recorded by Stow in his Survey of London as follows: "About the reign of Henry VIII three brethren that were gunfounders surnamed Owen, gat ground there ["Houndsditch"] to build upon and enclose for the casting of brass ordinance. These occupied a good part of the street on the field site." The same author in his Annales states more definitely under the year 1535 that: "John Owen began to make brasse ordinance as cannons, culverines and such like, hee was the first Englishman that ever made that kind of artillerie in England. His issue of his name and the name of Pitt have continued unto the dayes of King James, most ready and exquisite gun makers." Stow is evidently desirous of giving credit to the Owens as being the first Englishmen to produce bronze guns, but pride of place must certainly be given to Humphrey Walker who had been casting them in 1512. Possibly the Owens had graduated under Walker or Baude for, if Stow's date of 1535 is correct, six years before, in 1529, they were paid £8 for a brass "fawconnette". The supposition therefore is that they worked in the first Houndsditch foundry under Walker or Baude and then set up business for themselves in the same street. At any rate they must be considered to be among the most important of English gun-founders in the whole history of the craft. ...

In 1540 John Owen, who was either the father or the elder brother, makes a petitition respecting his patent from the King for making ironwork. This seems to be distinct from gun-founding but no further details are given. In the same year the brothers John and Thomas receive the title "Bombardarum nostrarum fabricatori", and in 1546 on the death of Peter Baude they are recorded as his successors in the office of King's Gun-founders with all the profits relating thereto. As Robert's name does not occur after 1540 he presumably died or retired before this date.

In 1553 two of the gunners of the Tower, Gilbert Pott and John Owen, attempted to pass through St Mary's Lock, London Bridge, the eighth arch from the northern end, on their way to Blackfriars, in a wherry. The current in these arches was alway dangerous and in this case the wherry was capsized and both Pott and Owen drowned, though the boatmen saved themselves by holding on to their oars. Appended to the entry dealing with the appointment of the Owens as Royal Gun-founders is a note, dated 1571, which states that Thomas, surviving brother of John Owen, resigns his office as King's Gun-founder; and with his name the record of Houndsditch as a gun-foundry closes.—pp. 47–49