The Royal Arsenal at Woolwich dated from the late 17th century and at the time of the First World War covered 1,285 acres and employed close to 80,000 people. It finally closed as a factory in 1967 and the Ministry of Defence moved out in 1994. Today it is open to the public and is being redeveloped for housing and community use. A full history can be seen at https://en.wikipedia.org/wiki/Royal_Arsenal
The Shell Foundry Gates were cast for the Shell Foundry at the Regents Canal Iron Works in 1856. They were removed on the closure of the Royal Ordnance Factory at Woolwich in 1966 and re-erected at the Royal Ordnance Factory at Patricroft. They were returned to the Royal Arsenal at Woolwich by the Royal Ordnance and recommissioned on 31st May 1991. They now stand on the edge of Wellington Park.
The gun on the left is a 24 pounder manufactured at the Carron Company in Falkirk, Scotland. It is said to have been employed at the Siege of St Sebastian in 1812. There is a large dent in it where it was hit by a cannon ball which killed the gun layer. A close up of the gates can be seen at https://www.geograph.org.uk/photo/5694836