What is the relationship between Vodafone 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.

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

Answer: headquarters_location