Online sales across the UK, US, Germany and China will grow by £320bn between now and 2018, increasing the value of the online market to £645bn, according to research by OC&C Strategy Consultants, PayPal and Google.

Brits are currently spending nearly £1 in every £5 of their shopping via the web and the new survey suggests that ecommerce will continue to flourish.

Burgeoning online sales will be boosted by smartphones and retailers that invest more in the digital side of business.

59% of online sales are now through smartphones or tablets in the UK, in the US this number is 45% and in Germany it‘s 24%.

Leading British retailers will benefit from the steady increase in overseas sales, as the research found that Chinese shoppers now purchase products online from British retailers almost as frequently as domestic shoppers do. British brands are the most popular internationally for German consumers, and the second most popular in the US and China.

Anita Balchandani, Head of Retail at OC&C, said: “The study has shown that UK retailers are some of the world‘s most popular and are in a strong position to seize more opportunities abroad.

“But at the moment, the majority are only doing the basics to adequately serve foreign markets, for example, by offering international delivery on their UK website and working with partners to provide local returns addresses.”

International shoppers cited choice of product, pricing and the quality of British goods as reasons for buying overseas, while concerns included data security and the inability to return unwanted products.

Martijn Bertisen, Sales Director at Google UK, added: “The number of people with internet access is growing fast, with many new consumers skipping the desktop phase entirely and only experiencing the web through a smartphone.

“Our study shows that this is increasingly translating into mobile transactions and that a mobile-first or even mobile-only strategy is now imperative to international success in retail. UK retailers should be well positioned to lead this growth internationally, as UK consumers are already amongst the most mobile of all.”

Cameron McLean, Managing Director at PayPal UK, added:

“British businesses have more opportunities than ever to capitalise on the international online shopping market, provided they can offer the right levels of security, trust and translation to build consumer confidence. Last year we launched PassPort, a website designed to show businesses new opportunities in foreign markets, and equip them with the tools and knowledge to grow their international sales.”