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

Neil continued, “The southern sales team has further expanded to enhance our coverage throughout the region, with three key appointments in London and a new Head of Sales.

Answer: headquarters_location