China's HNA: The biggest company you've never heard of

China's HNA Group is quickly becoming one of the world's biggest companies, but the chances are you will have never heard of it.

It has gone on a multi-billion dollar spending spree in recent years, snapping up dozens of businesses as well as major stakes in Deutsche Bank, hotel chain Hilton and skyscrapers in London.

The Chinese conglomerate now employs more than 400,000 people worldwide and has ambitions to grow even more.

HNA chief executive Adam Tan told the BBC it had "full confidence" in its approach, despite threats of tighter spending controls on Chinese businesses and the prospect of Brexit in the UK.

The company's strategy involves buying businesses all along the supply chain.

That means when you travel, for example, your luggage might be handled by one of its firms, you could eat aeroplane food from its catering group Gate Gourmet, or stay in one of its hotels.

"That's our business, from the airlines business, airport business, shopping business and travel agent business," Mr Tan says.

'Confidence in UK'

As well as the travel industry, HNA also has a sprawling property portfolio.

One of its major deals last year was to acquire two large buildings in London's Canary Wharf.

That deal was shortly before the Brexit vote, but Mr Tan says he continues to see strengths in the UK economy.

"Before I bought the two buildings in Canary Wharf, we had full confidence in London and the UK.

"I've still got huge confidence. The UK inside the EU or outside the EU, [the] UK is [the] UK," he says.

HNA Group owns Hainan Airlines, one of China's biggest airlines

HNA, which is led by Chinese billionaire Chen Feng, was founded in 1993 and made its name in shipping and aviation.

It has achieved its breakneck growth without the help of Chinese government money, Mr Tan says.

For that reason, he is sanguine about plans by Beijing to tighten restrictions on Chinese businesses spending money abroad.

He says HNA will still get support from Chinese banks, and can count on international banks as well because of its large presence outside of China.

With the support of banks such as JP Morgan and Goldman Sachs, it can continue to fund its future growth, he says.

"We don't feel so much pressure on that," he adds.

What has HNA bought?

• Biggest shareholder in Deutsche Bank

• A 25% stake in hotel group Hilton

• Airport services firm Swissport Group

• Carlson Hotels, which runs the Radisson hotel chain

• Airline catering firm Gate Gourmet

• Irish aircraft leasing firm Avolon Holdings