The collapse of Jamie Oliver’s UK restaurant empire is a major blow to the celebrity chef who became a household name after he was talent-spotted at London’s River Cafe by a TV crew in 1997.

The Essex-born chef began his own restaurant empire in 2002 with the opening of Fifteen, where he trained unemployed young people at a fashionable London dining establishment.

The more mass market Jamie’s Italian was founded by Oliver and his Italian mentor, chef Gennaro Contaldo, in Oxford in 2008. The concept was an instant hit, with diners queueing around the block, and the group went on to open dozens around the country.

However, appetite for the chain waned as it faced rising competition from numerous Italian-inspired rivals such as Pizza Express, Strada and, more recently, Franco Manca.

The market has become crowded after private equity investors piled money into casual dining chains, as consumers switch spending to experiences like meals out and holidays instead of buying clothes and homewares.

But that growth has waned since 2016, as consumers have become nervous amid the uncertainty of Brexit, while the rise of delivery services such as Deliveroo and JustEat have encouraged the Netflix generation to stay at home on the sofa with a takeaway.

Jamie’s Italian first showed signs of trouble in 2017 when it closed six outlets in the wake of the Brexit vote and as its relatively expensive prices and unexciting menus failed to stand out from the crowd. The chain made a loss of nearly £30m that year and the chef pumped £13m of his own money into the restaurant business as part of efforts to keep it afloat.

The following January, the group announced a restructure involving the closure of 12 more Jamie’s Italian outlets and put the Barbecoa chain into administration, with only one of its three outlets surviving.

With trading still tough, Oliver hired advisers in February to seek new investors for the restaurant business. Potential buyers did come forward and the chef put up another £4m of funds, but no suitable deal could be found.

The subsequent collapse of his restaurant group is not the first setback for Oliver who has admitted that 40% of his business ventures were failures.

In 2015, he shut the last branch of Recipease – his chain of cookery shops – and the last of his four British-themed Union Jacks restaurants went the same way two years later.

But Oliver retains a wide range of lucrative culinary business interests, ranging from recipe books to pans. He paid himself £6m in dividends in 2017 as profits from his books and TV programmes rose, offsetting losses at his restaurant empire and a fall in profits from licensing.

• This article was amended on 22 May 2019 to clarify that Jamie Oliver put in another £4m of funds to support the business when it was attempting to find a buyer