Utilize the input text as a context reference, choose the right relationship between Worldpay and London from the options. Options: product/material produced, manufacturer, distributed by, industry, position held, original broadcaster, owned by, founded by, distribution format, headquarters location, stock exchange, currency, parent organization, chief executive officer, director/manager, owner of, operator, member of, employer, chairperson, platform, subsidiary, legal form, publisher, developer, brand, business division, location of formation, creator.

** British payments processor Worldpay Group listed on the London Stock Exchange on Tuesday in an initial public offering valuing the company at 4.8 billion pounds ($7.4 billion), the biggest flotation in London this year.

Answer: headquarters_location