Chinese tourists doubled spending while visiting Britain in the months after the UK's vote to leave the European Union, according to a survey by Global Blue, a tax refund firm.

The survey shows that Chinese visitors now make up 33 percent of tourists taking advantage of duty-free purchases in the United Kingdom, and that they increased their spending by 103 percent in February, due almost entirely to the fall in the value of the pound since the Brexit vote. The pound has slipped 15 percent against the US dollar since June.

Chinese flight bookings to the UK in January rose 81 percent year-on-year, according to travel analysts at ForwardKeys, and for the first three months of this year, Chinese flight reservations to the UK were 43 percent up on last year.

Jo Leslie, who runs the Great Chinese Welcome Programme for the government agency Visit Britain, said:"Chinese tourists in London spend twice as long there as they do in mainland Europe, spend twice as much money, and the numbers are growing at twice the rate."

In the UK, shoppers can make duty-free purchases if they have a permanent address outside the EU. Until recently, they had to pay the duty at the time of their purchase and claim it back at the airport before leaving.

Global Blue, a tax refund specialist, recently struck an agreement with UnionPay, which provides card and transaction services for most Chinese banks. Many Chinese tourists can now pay for goods when they visit Britain and either get a transfer straight to their bank card, as long as it has a UnionPay logo, or get an immediate refund while still in country, provided they claim, with receipts, from specific payment points.

The new system completely eradicates queuing at airports and waiting for weeks for a refund payment to reach a claimant's account, according to Global Blue.