“Why on earth do you want a cannon?” my wife asked when I explained that I had spotted the sweetest little example, just looking for a new home, in a local antiques shop. Married to an avid collector of ancient armour and weaponry, she is fairly inured to bits of what she deems “rusty metal” occasionally being snuck into the house. However, a 19th-century working naval cannon? Little chance of slipping that in undetected; none at all of keeping it hidden. Anyway, why would I? In the world of big boys’ toys, if you’ve got cannon, flaunt it.

“We mount it facing the front gate and if we like our visitors we fire confetti, if we don’t we give them a broadside of rotten fruit,” I suggested. That raised a laugh and a grudging acceptance that having cannon outside your door does add a certain je ne sais quoi to a property, although perhaps not the sort your average estate agent might recommend. I deemed that one laugh justification enough and, £500 later, I was facing a problem all buyers of cannon need to get their heads around. While my new “baby” is relatively puny in the world of ship sinkers – just over 3ft long and made of cast iron – it still weighs around half a ton. It took three men, a trolley and an almost broken leg (mine) to manoeuvre the remorseless lump of metal into my Range Rover without further damaging us or it. Anything larger and I would have needed a low-loader.

The next step was to establish what would be involved in firing it. It doesn’t take a huge IQ to realise that the inhabitants of our sleepy village might jump to the wrong conclusion and call the local constabulary were I to start test-firing my 6-pounder. A friend had already told that “scientific’ childhood experiments with a cannon and a dead cat – to see how it would impact against a wall – had resulted in a vile-smelling red mist, and wooden posts splintering. Black powder demands very hard projectiles.

I envisaged cricket balls, or similar, and that meant access to the wide green yonder. The boys on my shoot demanded to be at the “grand opening” and a farmer mate agreed to host the event. Things were looking up.

I mentioned my cunning ideas in a local gunshop. The staff looked at me as if I had taken leave of my senses. First they mentioned the rules of buying black powder (special licence required); moving it (a second licence); and storing it (it should be kept in special wooden boxes and there should be no contact with metal as the powder is highly susceptible to sparks – debatable as it turns out).

Did I know how powerful black powder could be? Apparently some over-refreshed joker once celebrated winning a trophy by firing the cannon outside Canada House in Bisley. He got some powder and, using a wet loo roll as a projectile/tamping device, added flame to the touch-hole. The soggy roll flew clean over the ranges and broke the window of a caravan on the far side.

Bill Harriman at the BASC was almost shocked into silence when I rang to get some advice. Did my cannon have a bore over 2in he asked. “Yes,” I answered with pride. Then, he told me, the moment I went to fire it – “intent” might be enough, this area of the law is slightly grey – it would be designated a firearm under the Firearms Act (under 2in bore and it would require a shotgun certificate). Firing it without a firearms licence would be an offence. In an instant my dreams of a champagne-fuelled grand firing evaporated – rather like that long dead cat.

The good news was that as long as I kept it as an ornament or curiosity then it was exempt under the Act and I could legally own as many as I wanted. I tested him further. How about putting something else down it and going for a puff of smoke? A big firework perhaps? He was having none of this.

Getting a licence would not be easy. All those questions the firearms officer asks about “good reason to possess” when licensing a rifle would be asked about a cannon, and different police forces might interpret the law differently. Having my own large estate would have been a useful start. That said, he did know of someone who had a licence for a cannon which he showed off and fired at village fêtes and could be hired to blow the ashes of the dearly departed to the four winds – giving a somewhat different interpretation to the term “going out with a bang”.

Despite the severe limitations on firing them, cannon are highly collectable and regularly come up for sale at specialist arms and armour auctions. David Williams of Bonhams auctioneers says that you should reckon on a minimum of £1,000 to buy a small, plain iron cannon. It is usually “the bigger the better” but that has to be tempered with quality and provenance; an example from a known battlefield or a famous owner should always attract a premium.

At the top end, cannon are works of art – albeit once lethal works of art – fabulously cast with intricate figures in bronze. However, a small and beautifully made example will be worth far more than a large, boring one. Williams sold a wonderful French, 19th-century, engraved bronze field gun for £21,600 in his 29 April sale. Alternatively, and only for those with access to low-loaders, Thomas Del Mar (in association with Sotheby’s) has three massive bronze cannon in his 30 June sale. Cast in the early 17th century, each weighs approximately 31⁄2 tons and is more than 10ft long. Estimates range from £12,000 to £20,000.

If you like cannon, you’ll think Nick Hall, Keeper of Artillery at Fort Nelson near Portsmouth, has the ultimate job. When The Royal Armouries was split up, many guns – including some from the Tower of London – ended up at this 1860s fort overlooking the Solent. He has more than 350 pieces ranging in date from Gerald Bull’s super cannon, with which Saddam Hussein planned to lob nuclear and chemical shells clear over Jordan and on to Israel, right back to early examples such as Mons Meg from the 15th century. Outside the fort there are two of the biggest guns that you will ever get to see: Mallet’s Mortar (with a 36in bore), a siege gun made for the Crimean War, and a naval gun of the type used on King George V battleships (14in bore). Twice a day in summer (once in winter) visitors can watch a live firing.

The more Nick told me about the risks and mechanics of firing cannon, the more I realised that this was best left to the experts. It takes great skill just to get the powder correctly packed in bags and rammed into the end of the tube so it can be ignited through the touch-hole. After each firing the gun must be cleaned out and swabbed. Too much water and the barrel is soaked. Too little and should you ram a new bag of powder on to still smouldering residue there will be an instant detonation. The rammer becomes the projectile and, the loader could lose a hand or worse. Accidents happened when these beasts were fired in earnest and still happen when safety rules and firing drills are not followed.

Having seen his incredible collection I felt somewhat subdued showing Nick photos of my little cannon. He still enthused: it was 19th century, probably carried by a merchant ship for anti-piracy protection and designed to fire point-blank at approximately 100 metres. It was, however, a lucky survivor as most large guns were broken up, thrown overboard or melted down when they became obsolete.

The most likely place to find cannon is at auction.

Check out both maritime/marine sales and arms and armour departments as they crop up in both.

www.bonhams.com; 020 7393 3900
www.charlesmillerltd.com; 020 7806 5530
www.christies.com; 020 7752 3119
www.enquiries@thomasdelmar.com; 020 7602 4805
www.wallisandwallis.co.uk; 01273 480208