Chinese investment in London commercial property has more than trebled since before Britain voted to leave the European Union, most of it channelled through Hong Kong at a time of heightened political uncertainty in the former British colony.

While others have pulled back from British property following last year’s Brexit referendum, investors largely from Hong Kong are snapping up the British capital’s best-known skyscrapers including the “Cheesegrater” and “Walkie Talkie”.

In the first six months of 2017 Chinese investors spent STG3.96 billion ($A6.42 billion) on London commercial property according to data from the CBRE real estate group, the highest amount on record and outpacing the 2.69 billion pounds spent in the whole of 2016.

Hong Kong accounted for 92 per cent of the Chinese investment, according to the Knight Frank agency. Hong Kong food conglomerate Lee Kum Kee is set to pay 1.28 billion pounds later this month for 20 Fenchurch Street – the 34 storey skyscraper known as the Walkie Talkie – a record for an office building in Britain.

With Beijing cracking down on foreign deals by mainland companies, investors there are instead using Hong Kong as a conduit for overseas deals. China’s state planner announced on Friday that the country will strengthen rules to defuse risks for domestic companies investing abroad and curb “irrational” overseas investment.

However, Hong Kong-based investors are more significant players.

“Deals from mainland China already make up a smaller proportion of the activity from the region, with Hong Kong investors most active,” said Anthony Duggan, head of capital markets research at Knight Frank. “We expect that Chinese investors will still look to make strategic real estate purchases that fit within their business plans.”

Hong Kong’s freedoms, including judicial independence, are constitutionally enshrined under a “one country, two systems” deal struck before Britain returned the territory to China in 1997. However, concerns have been rising in recent years and an appeals court jailed three leaders of Hong Kong’s democracy movement last week.

Tens of thousands protested in Hong Kong on Sunday against the jailing of the young activists, with many demonstrators questioning the independence of the judiciary.

“If you’re concerned that China is taking control of Hong Kong more and more and you need to take capital out of that jurisdiction, London is attractive,” said Chris Brett, head of international capital markets at CBRE.

Several factors are drawing the investment, including sterling’s 12 per cent drop since the Brexit referendum against the US dollar – to which the Hong Kong dollar is pegged.

“Cheaper money, the rule of law, cultural familiarity and a need to diversify out of a home market is what’s driving Hong Kong demand in the UK,” said James Beckham, head of central London investment at property consultant Cushman & Wakefield, which advised the Walkie Talkie’s buyers and Cheesegrater’s sellers.

Record Hong Kong commercial and residential property prices, along with the political concerns are pushing investors to turn to overseas markets where rental yields are higher.