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.

Market Movers techMARK 3,077.19 -0.94% FTSE 100 6,327.65 -0.63% FTSE 250 17,101.31 -0.80% FTSE 100 - Risers Johnson Matthey (LSE: JMAT.L - news ) (JMAT) 2,720.00p +1.08% Randgold Resources Ltd. (RRS) 4,289.00p +0.80% Fresnillo (Amsterdam: FN6.AS - news ) (FRES) 688.00p +0.51% Hikma Pharmaceuticals (LSE: HIK.L - news ) (HIK) 2,424.00p +0.21% Sainsbury (Amsterdam: SJ6.AS - news ) (J) (SBRY) 246.30p +0.20% GKN (GKN (LSE: GKN.L - news ) ) 290.50p +0.17% Land Securities Group (LAND) 1,301.00p +0.15% Rio Tinto (LSE: RIO.L - news ) (RIO) 2,363.00p +0.08% Morrison (Wm) Supermarkets (MRW) 169.10p +0.06% FTSE 100 - Fallers ARM Holdings (LSE: ARM.L - news ) (ARM) 867.00p -3.34% St James's Place (STJ) 931.50p -1.90% Mondi (MNDI) 1,460.00p -1.88% ITV (ITV (LSE: ITV.L - news ) ) 249.40p -1.81% London Stock Exchange Group (LSE) 2,511.00p -1.61% easyJet (EZJ) 1,675.00p -1.59% Carnival (CCL) 3,306.00p -1.55% Wolseley (EUREX: WLYH.EX - news ) (WOS) 4,145.00p -1.54% Shire Plc (Xetra: S7E.DE - news ) (SHP) 5,000.00p -1.48% RSA Insurance Group (RSA) 500.00p -1.38% FTSE 250 - Risers Lonmin (LMI) 37.01p +4.93% Polymetal International (Other OTC: AUCOY - news ) (POLY) 476.40p +2.12% Tullow Oil (LSE: TLW.L - news ) (TLW) 207.40p +2.02% Fisher (James) & Sons (FSJ) 1,124.00p +1.81% Acacia Mining (LSE: ABG.L - news ) (ACA) 264.70p +1.73% Genus (GNS) 1,374.00p +1.70% SIG (Stuttgart: QIG.SG - news ) (SHI) 188.90p +1.67% Wood Group (John) (WG.)

Answer: headquarters_location