It is one the biggest things to come out of Liverpool since the Beatles. The Home Bargains discount empire has turned its founders into multi-billionaires, but you would be hard-pressed to name them despite their family fortune being greater than those of Sir Philip Green and Mike Ashley added together.

Both in their 60s, brothers Tom and Joe Morris are the cut-price high street kings with 500 shops and an empire valued at £3.6bn. This week it emerged the company had paid a £10m dividend to its owners last year, after their Woolworths-style chain - which sells everything from toiletries and dress-up costumes to furniture, cake mixes and £1,000 outdoor pizza ovens - went from strength to strength despite grim high street trading conditions.

At a time when the big supermarkets are finding life tough and even some discount rivals are under pressure, Home Bargains made £233m profit last year, up 15%. The chain raked in sales of nearly £2.5bn and set a target of building the business up to 1,000 stores.

Tom Morris, who owns 90% of Home Bargains parent TJ Morris with the other 10% in a family trust, studiously avoids the limelight. One of the few photographs in circulation of Tom is the businessman awkwardly posing with some Morecambe pupils after being allowed to land his helicopter on their school field to visit a new store nearby.

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“Tom is very impressive,” says one business associate. “There is a humility to him that is very admirable. He is very private and does not flaunt his wealth.”

Any public speaking – and there is very little of it – is left to Joe Morris, a younger brother and operations director. Joe’s claims to fame include sponsoring the Liverpool tapestry created for the European Capital of Culture celebrations. At 7 metres (23ft) in length, the work comprises 338 panels and includes one he stitched himself – of a Home Bargains shop front.

The family appear to own few of the trophy baubles usually associated with vast wealth. There is, however, a private jet, with M-ORIS spelled out on the tail. Over the past year the aircraft – big enough to seat a dozen passengers – has regularly crisscrossed the UK, visited a remote region of Brazil and touched down in New Jersey.

Even so, the Morris family are described as “down-to-earth” people who would not want to alienate their customers and staff by living a flashy lifestyle.

Tom Morris, owner of Home Bargains.

The brothers are two of seven children of a Liverpool shopkeeper, Tom senior. That store was called V’s after Veronica, their mother, and for “value”.

Tom junior opened a shop of his own in the Old Swan area of Liverpool in 1976 when he was just 21. His siblings initially sought other careers, with Joe, an engineering graduate, once explaining: “I had never been further than holidays in Rhyl. I wanted to get away from shops and see a bit of the world.”

But he eventually returned to the fold and became Home Bargains operations director. Their brother Ed, who has a computing doctorate, wrote software for the company, which is now said to have hi-tech warehouses envied by rivals. (He no longer works for the firm.) Another sibling, Anton, is a successful graphic artist who came up with the company’s original branding.

Home Bargains has grown steadily and conservatively from its north-west base over the past 40 years. While many rival retailers are struggling under huge debt piles and are trying to cut their rent bills, Home Bargains is debt-free, owns many of its stores and insists it does not “engage in aggressive tax planning”. Last year it paid corporation tax of £49m, nearly double the amount paid by Facebook’s UK operations.

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Over the years Tom, who owns a flat in Liverpool’s Albert Dock, has built a substantial commercial property empire, including shops on the city’s swish Falkner Street. Another of his companies recently paid £3.8m for a rail depot in Ashford, Kent.

On a mid-October Thursday afternoon, the Home Bargains store in Hounslow, west London, is doing a brisk trade with the after-school crowd. There are Halloween props galore, but in the neighbouring aisles it is already Christmas. The shelves are filled with decorations and cheesy festive knits.

Natasha Stead is out with her father Tony, doing their weekly “Home Bargains Shop”. She calls it “selective shopping” and their eclectic haul includes dog food, jam and Coke.

“You always pick up something,” she explains. “I think there is a stigma attached to shops which have the word ‘bargain’ in the title. But you can buy the branded stuff if you are worried. I don’t worry about that though, I’m a teacher and on a budget.”

The Morris philosophy is simple: “If we can’t sell it cheaper than the competition, we wouldn’t sell it,” Joe once told the Guardian, then added: “It’s easy to sell stuff cheap … the hard part is making money out of it.”

The chain’s mantra is “top brands at bottom prices” and like rivals such as Aldi, Lidl and Poundland, the business benefited from the 2008 financial crisis which opened the eyes of cash-strapped Britons from all income groups to the bargains to be had in discount stores. “A lot of people are time-rich, money-poor and shop around,” explained Joe.

Suppliers are encouraged to turn up at the firm’s head office in Gilmoss, Liverpool, where buyers make quick decisions. “When you go on to the trading floor of their head office, it is all open plan and Tom’s desk is the first one you come to,” said one business associate.

But what does the future hold for the business? Tom, whose children work in the business, turned 65 this year while Joe is 60, so the question of succession looms large. City investment banks have been knocking on the Morrises’ door, keen to sell the idea of a stock exchange listing, but, so far, they have not been tempted.