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

LONDON (ShareCast) - (ShareCast News) - Oil and gas explorer Roxi Petroleum (Other OTC: ROXIF - news ) has reached an agreement to cancel royalty payments from its flagship asset.

Answer: headquarters_location