The pots of gold at the east edge of London

On occasion, the chauffeur-driven Rolls-Royces, Bentleys and high-end Mercedes can be seen navigating the roundabouts of an east London industrial estate squeezed between Europe’s largest sewage treatment plant and the remains of the world’s once-largest gas works.

While the fancy cars are an incongruous sight in this Beckton industrial estate, the drivers have not lost their way. They pull up outside a nondescript blue and grey warehouse opposite a FedEx parcel collection hangar. The warehouse looks like all others on the estate, but on closer inspection it bristles with CCTV cameras with the doors surrounded by 12ft metal security barriers capable of stopping a truck.

The rich are driven here to inspect their gold. “They come in here, they inspect [their gold bars] and caress them,” says Lorena Baird, executive director of the Baird & Co, the UK’s only gold refinery which has been operating quietly in east London for half a century. “Each customer has an individual box and we bring it to them here so they can see and feel their gold.”

Baird, 50, said it’s not just the super-rich who are turning to gold as a safe haven investment in this increasingly turbulent world. “Our customers can be anyone from a grandmother to a billionaire,” says Baird, who took the helm following the death of her husband, Tony Baird who founded the company in 1967 . “Whatever happens in the world, there’s one thing you can be certain about – people will still want to buy gold.”

Every time there’s a major global event, the price of gold sparks and the phones in Baird’s warehouse ring. The last time the price rose significantly was last month when President Trump warned North Korea not to “try us”.

“North Korea, Brexit, whenever something big happens, it is reflected in the [gold] price,” Baird says. “Gold is a hedge against inflation; gold is the safe haven.”

There is gold everywhere in the Baird warehouse, where pawned jewellery is melted down and refined into fresh gold bars. As well as producing gold bars, the company also makes gold sovereigns, 50,000 rings a year and collectables on demand. In 2013, Cadbury commissioned Baird to make 18-carat gold replicas of its most popular chocolate bars – that were given away to customers à la Charlie and the Chocolate Factory.

As well as producing gold, platinum and rhodium (a slivery white metal in the platinum family which is rare and more expensive than gold), the company holds the nation’s biggest private gold vault. Baird says she’s unable to state how much gold is currently on the premises for security reasons, but it is hundreds of millions of pounds worth.

Most of the gold is formed into 1,000-gram bars stamped with Baird’s seal and kept in the vault. A gold bar is much smaller than you might expect – thinner and shorter than an iPhone 6, but much, much heavier. A very satisfying weight.

Baird’s bars, she says, are actually slightly heavier than the 1,000-gram standard as the company prides itself on the quality of its bars and can’t risk a customer bringing their own scales and catching the firm out. How much, heavier? Like a gram? Baird bursts out laughing. “No!” Each gram of 24-carat gold is worth £27.93 at the time of writing, and none of it is wasted.

“Don’t sneeze,” Baird warns at one point as she shows the Guardian the full process of how trays of broken, discarded pawnbroker jewellery of varying quality are transformed into a new bar of ultra-fine gold. It is impossible to achieve 100% purity and 999.9 gold (or 99.99%) is the closest refiners can get. The purity needed for 24-carat designation is 99.95%.

The bucket of brown sand she’s holding contains 6kg of gold (worth about £160,000). The gold sand is the product of Baird’s “Willy Wonka” refining process that converts jewellery that arrives with an average gold content of 37% to the 99.9% purity product.

It’s a multistage process involving heating the gold up to 1,200C or more and mixing it with a lot of acid. Parts of the process, carried out by Baird’s 62 employees dressed in blue overalls, have little changed since the ancient Egyptians invented it.

Despite the intense industrial processes, Baird says waste water leaving the factory is cleaner than the drinking water coming out of its taps. Any incoming gold that contains cadmium, mercury or other toxic metal is rejected. The firm employs a chemist to analyse the molecular make up of all gold shipments coming in and all waste leaving.

Under almost every machine is what looks like a cat litter tray. But there are no factory cats (the Guardian’s photographer inquired just to make sure). The trays are there to absorb any waste water leaking out of the machine, because the water is likely to contain enough quantities of gold to make it worth keeping. “There is gold everywhere, it is in the air,” Baird says.

To keep as much gold in the building as possible, workers are asked to take off their overalls at the in-house laundry before they go home. The laundry is equipped with regular looking washing machines, but the waste water is pumped through filters to capture any gold particles. There are also filters attached to all the ventilation shafts.

“At the end of the year all of the filters are collected together and burned,” Baird says. “Everything is ‘deep cleaned’ and burned, all of the filters and all of the doormats both inside the refinery and throughout the office.” Last year the company retrieved £15,000 worth of gold from the deep clean.