What is the relationship between G4S and LONDON in the context of the input sentence. Choose an answer from: 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 (Reuters) - Britain's G4S Plc (GFS.L) said it won a $187 million contract to provide security services to a gas plant in Iraq, while in Afghanistan, it renewed a contract to provide protection to the British government.

Answer: headquarters_location