History of Powell Anvils
Likely produced anvils from ~1750-1770 out of Saint James Clerkenwell, Middlesex in London. 
1754 or Jan/Feb 1755 –
Thomas Bird exits the anvil making process and sells or rents his shop to Thomas Gravell as well as selling him much of his stock.
Samuel Bird, a relative of Thomas, seems to leave the shop on Goswell street and setup a new shop nearby.
1755 – Mar 11, 15, 20
Thomas Gravell posts an advertisement about his
Whereas I Thomas Gravell, late of Cow-Cross, Tool-Maker, have bought the Stock of Mr. Thomas Bird, Anvil-Maker, at the Anvil and Cross-Hammers in Goswell Street near Old-Street, London, where the same Business, both of Anvil-making and Tool making is carried on as usual, Those Gentlemen that please to favour me with the Commands shall be well used and have their Work well done, warranted sound and good, and at that lowest Prices.
N. B. It has been falsely and maliciously reported that Mr. Bird’s Men had all left the shop which is entirely without Foundation and the Forman, and greatest Part of the Workmen are now with me, and Mr. Bird himself, when he sees Occasion will assist.
1755 – Apr 12th – Ipswich Journal
Thomas Bird leaves his business and rents his shop to his kinsman Samuel Bird.
Whereas Mr. Thomas Bird, Anvil-Maker, of Goswell-Street, London, has left off Business and let his Shop to a Tool-Maker; the business is carried on by his Kinsman Samuel Bird, at the Anvil and Cross Hammer in St. John’s Street, London, who served a regular Apprenticeship with him, and as a Journeyman for four Years, after being Manager and Sinisher great Part of the Time; therefore those Gentlemen that please to favour him with their Orders, may depend upon being used well, and to their Time, and warranted good and found for one Year.
N.B. Any Person in the Country my, by a Letter, have his Buisnnes done as well if present, and at the most resonable Rates, by their humble Servant,
1759 – Supplied anvil to a Louisa County, Virginia blacksmith 
1771 – Dec 13th Will for Samuel Bird