Utilize the input text as a context reference, choose the right relationship between Vodafone 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.

Vodafone Australia's head of fraud Colin Yates emailed Vodafone Group in London to discuss the illegal activity.

Answer: headquarters_location