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

The London firm is not alone in this regard, naturally, as fellow explorer and producer Tullow Oil (LSE: TLW) will attest to.

Answer: headquarters_location