The factory , based at Hounslow but actually nearer Twickenham closed (I think ) in 1927 presumably because of urban encroachment. The location was to the West of London in an area best described today as in the vicinity of Heathrow airport.
The need to establish an independant supply of gunpowder dates back to the time of Henry VIII and the mills at Houslow were a private venture but supplied the Government.
They were reliant for their nitrates on urine bought in bulk from the population of London and rendered down to provide the nitrates that were so vital to the production. There was no other source.
There is an expression , still used in the English vernacular, to describe extreme povert as being “piss poor”. People who sold their urine for money. They also sold it to the leather tanning industry based in East London
Of course all that changed over the years and supplies of nitrates were found in Chile and imported.
However, in those days the supply of gunpowder was so tenuous that a single naval or land engagement would render a second engagement impossible for a year or so until supplies were replenished. Part of the reason why archers remained the mainstay of British forces for as long as they did.
Sir Francis Drake’s defeat of the Spanish Armada used up all their supplies of gunpowder and effectively ended when it did because they ran out of powder. Had the weather not intervened, blowing the Spanish fleet out into the English Channel Drake would have been unable to fight on. The Spanish ships were not provisioned for a long sea journey and the crews starved trying to get back to Spain.
skip to the bottom of the page and select “shot towers”
then skip to the bottom again and select “crane park shot tower”
After 1927 the name Curtis & Harvey passed into the ownership of ICI (Nobel industries) best known as Eley Kynoch but the fact that your tin says Hounslow predates it to before 1927
The importance of being on the river Crane was also that the powder, once made, could be transported by boat down to the Thames. A distance of about 5 miles without being shaken about on a road journey.
See also the Royal Powder Mills in North London.
Powder from there was transported to the Thames by the river Lea