Rule of law benefits British investors in China

Economists also believe the anti-graft fight could benefit foreign companies operating in China as it will improve business practices.

"Anti-corruption helps the economy in the long run, as it reduces business costs," said Chang Jian, chief China economist with Barclays Plc in Hong Kong. "Just like corporate restructuring, it brings short-term effects but has benefits in the future."

As part of an effort to rebuild its image, GSK has announced major changes in its sales and marketing practices, according to Witty.

Particularly noteworthy was that GSK no longer ties the compensation of its sales representatives to the number of prescriptions written by the doctors they interact with. Instead, GSK sales reps will be paid based on their technical knowledge and the quality of service they provide to their clients.

"Some people are questioning the presence here, honestly, I believe they are making short-term decisions," said the GSK CEO, noting that the company will invest more in China.

The steady economic growth in China and Britain is a bright spot in a gloomy global economy. In the first eight months of this year, China-Britain trade volume reached 50.6 billion U.S. dollars, according to statistics from Chinese Ministry of Commerce.

Britain has become China's second largest investor and trading partner within the European Union. As of August, Britain had invested in 7,992 projects in China, with an actual investment of 19.61 billion U.S. dollars.

"It is a good time to invest in China, to learn and understand what the new normal really means in China, and to work with China to deliver good value to its people, then the company will do fine in China," said Witty, who is optimistic about China's economic prospects.

Ralf Speth, CEO of Jaguar Land Rover, also voiced confidence in the growth of the Chinese market in September.

Jaguar Land Rover, a British luxury car brand owned by India's Tata Motors, sold 122,010 cars in China last year, up 28 percent from 2013. The company also cited the Chinese market as the primary reason for its fifth successive year of growth in global sales.

The automotive industry is vital to the British economy. It has an annual turnover of over 60 billion pounds (88.43 billion U.S. dollars). Around 770,000 jobs depend on the industry, data from the Society of Motor Manufacturers and Traders Limited (SMMT) showed.

China has taken a number of steps to provide easier market access for inbound foreign investment and explore the possibility of management based on a pre-establishment national treatment (PENT) and negative-list approach, which means all sectors are open to foreign investment except those specifically listed.

PENT means that foreign investors and their investments will be accorded national treatment in the pre-establishment phase of their businesses. "Negative list" refers to activities to which national treatment and most favored nation status do not apply.