In the beginning gun powder for the military and Royal Navy was held by the Royal Artillery in the Royal Citadel in Plymouth.  But this presented a growing problem: the danger of transporting explosives through the streets of Plymouth and East Stonehouse from the Royal Citadel to the Army and the Royal Navy in Devonport.

This problem was solved in around 1784, when a Powder Magazine was built at Keyham, then in open countryside.

The earliest description of it dates from 1812:

'The Powder Magazine, which lies on the same side with the dock-yard, but much higher up the river, insulated from all other buildings; it consists of several detached stone buildings, erected with every precaution, to prevent accidents by fire or lightning.

This establishment consists of the Storekeeper, W Lawrence; Clerk of the Cheque, Peter Glinn; Clerk, John Clover, who have excellent houses, very pleasantly situated, for their residence.'

By 1815 the need for gunpowder and shot had outgrown the facilities at Keyham and five old hulks had been fitted out for storage purposes and moored in the Hamoaze.  Needless to say, this was highly dangerous as they were now closer to the men-of-war.

A later description dates from 1823:

'At Higher Keyham Point, a short distance from Morice-town, on the same side of the harbour, is the depot for gunpowder, for the supply of the government establishments at this port.  It is completely insulated from all other buildings, and consists of several detached edifices, which are constructed of stone, and otherwise erected with every precaution against accidents by lightning or fire.  These, we trust, will be found effectual, as the consequences of an explosion of the vast quantity of gunpowder which is here deposited, must be productive of the most terrifying consequences to the neighbourhood.

The whole of the depot covers a space of not less than five acres.  There is a neat row of houses at the back, which are occupied by the workmen, having been built especially for them'.

Rutger's "Plan of the Praish of Stoke Damerel in the County of Devon", dated 1842, shows the Powder Magazine on the southern shore of Keyham Lake where it joined the Hamoaze.  There was a small harbour by the side of a long building running north to south and several completely disconnected buildings, where the powder was probably stored.  To the south of the Magazine was a separate building or buildings surrounded by trees, which may have been residences for the principle officers.  The nearest houses were at Clarence Place and Charlotte Street.  The location approximates to the northern end of the Quadrangle in the Royal Dockyard.

When the Admiralty decided to construct a steam yard at Keyham they found that the Keyham Powder Magazine, which was the responsibility of the Board of Ordnance, stood in the way of expansion northwards.  It had to be moved.  One of the possible alternative sites was the old war prison at Millbay but, not surprisingly, both Plymouth and East Stonehouse did not want explosives that close to their communities.  In 1841 the inhabitants petitioned to have the Magazine removed and Colonel Oldfield of the Royal Engineers was ordered to find a new site for it.  As a result of his search the War Department bought some land at Bull Point, in the ancient parish of Saint Budeaux, adjacent to the  Keyham Powder Works, and there built the Army Ordnance Depot.