I set a small poser for fellow bloggers last night asking you to identify an old cannon... my chum Happy came up with the goods, so big congratulations to her. 
Here's a little about the history of this old beast...
HMS Foudroyant
The name is French for “thunder and lightning” and came from a captured French battleship in a single-ship action in 1758 by HMS Monmouth. She remained in the RN’s possession until broken up in 1787.
The second HMS Foudroyant was built and launched in Plymouth in 1798, as a second rate line of battle ship with 80 guns (Foudroyant's gun complement was variable throughout her career). Designed by Sir John Henslow (Surveyor of the Royal Navy) using the old French ship's design. Measurements were 2062 tons, 184ftx 51ft. Usual armament included 30 32pdrs, 32 24pdrs, 14 12pdrs and 12 carronades.
The cannon seen above is a 12pdr from the second HMS Foudroyant and would originally have looked like this in shipboard life.

Active Service
In her first commission, the second Foudroyant took part in Warren’s action off Donegal on 12 October 1798.
She became Nelson’s flagship in the Mediterranean in 1799-1800, and took part in the recapture of Naples from the French, the recapture of Malta and the taking of several French vessels.
In 1801, after a refit, she was Admiral Lord Keith’s flagship in the Egyptian campaign.
In 1803, she joined the Channel fleet after an extensive refit at Plymouth.
In 1808 she was Admiral Sir Sydney Smith’s flagship for his expedition to South America.
Foudroyant was finally paid off in Plymouth on November 30th 1812 and remained in harbour service.
Restoration, wrecks & relics
In 1862, Foudroyant was converted to a training ship and served the Plymouth gunnery school, HMS Cambridge. In 1892, she was sold for breaking up to a German firm.
Because of her association with Nelson, there was a public outcry including a Punch cartoon by Linley Sambourne. She was purchased by George Wheatley Cobb for twenty thousand pounds (his own expense) with a view for display at various ports and a sail training ship.
Foudroyant was wrecked at Blackpool in a gale on 16 June 1897. The salvage terms that the company involved received two thousand pounds only if they re-floated her. If they failed, they could buy the wreck for ten pounds.
The ship was deemed unsalvageable and the company recovered some of their expenses by making souvenirs from the timber and copper and selling them. Hundreds of different varieties were sold, including medallions, coins, items of furniture and walking sticks.

la_spice


I'm still waiting to hear which castle (my guess was Cheptow but I couldn't find any mention of a cannon!)