Exhibit 8.1

Our principal subsidiaries as of December 31, 2018, are listed below. All other subsidiaries, if considered in the aggregate, would not constitute a significant subsidiary under Rule 1-02(w) of Regulation S-X.

COMPANY NAME	JURISDICTION UNDER WHICH ORGANISED	OWNERSHIP INTEREST
United States
AKQA, Inc.	California		100
Mirum LLC	California		100
Possible Worldwide, LLC	California		100
Acceleration eMarketing Inc	Delaware		88
Arctouch LLC	Delaware		100
BCW LLC	Delaware		100
Benenson Strategy Group, LLC	Delaware		100
Bottle Rocket LLC	Delaware		100
Catalyst Online LLC	Delaware		100
Chi Wunderman Partnership LLC	Delaware		50
CMI Media, LLC	Delaware		100
Competitive Media Reporting, LLC	Delaware		100
DeepLocal Inc.	Delaware		100
Essence Global LLC	Delaware		100
Finsbury LLC	Delaware		100
Grey Global Group LLC	Delaware		100
Group M Worldwide, LLC	Delaware		100
Group SJR LLC	Delaware		100
GTB Agency, LLC	Delaware		100
Hill and Knowlton Strategies, LLC	Delaware		100
Hogarth California, LLC	Delaware		100
Hogarth Worldwide Inc.	Delaware		100
International Meetings & Science LLC	Delaware		100
J. Walter Thompson Company LLC	Delaware		100
J. Walter Thompson U.S.A., LLC	Delaware		100
Kantar Consulting LLC	Delaware		100
Kantar Health LLC	Delaware		100
Kantar LLC	Delaware		100
KBM Group LLC	Delaware		100
Landor, LLC	Delaware		100
Lightspeed, LLC	Delaware		100
Marketing Direct LLC	Delaware		100
Mediacom Worldwide LLC	Delaware		100
mPlatform, LLC	Delaware		100
Ogilvy CommonHealth Worldwide LLC	Delaware		100
Ogilvy Public Relations Worldwide LLC	Delaware		100
OpenMindWorld, LLC	Delaware		100
Penn, Schoen & Berland Associates, LLC	Delaware		100
PERQ/HCI, LLC	Delaware		100
Possible Mobile, LLC	Delaware		100
Promotion Execution Partners, LLC	Delaware		100
Rasor Holdings LLC	Delaware		100
Rockfish Interactive LLC	Delaware		100
Spafax Networks LLC	Delaware		100
Sudler & Hennessey, LLC	Delaware		100
Swift + POSSIBLE LLC	Delaware		100
Taxi Inc.	Delaware		100
Team Garage LLC	Delaware		100
The Exchange Lab Inc	Delaware		100
The Glover Park Group, LLC	Delaware		100
The Lacek Group LLC	Delaware		100
The Ogilvy Group, LLC	Delaware		100
Viscira, LLC	Delaware		100
Wavemaker Global LLC	Delaware		100
WPP Clapton Square, LLC	Delaware		100
WPP Group U.S. Finance LLC	Delaware		100
WPPIH 2001, Inc.	Delaware		100
Xaxis US, LLC	Delaware		100
Xaxis, LLC	Delaware		100
Young & Rubicam LLC	Delaware		100
Reese Communications Companies, Inc.	District of Columbia		100
Gorilla, LLC	Illinois		100
Triad Digital Media, LLC	Michigan		100
VML, LLC	Missouri		100
Wunderman Worldwide, LLC	Nevada		100
Geometry Global LLC	New York		100
GHG GreyHealth Group LLC	New York		100
GWE LLC	New York		100
Mindshare USA, LLC	New York		100
Ogilvy & Mather Worldwide, LLC	New York		100
WPP Montagu Square LLC	New York		100
Set Management, LLC	Oregon		65
Public Strategies, Inc.	Texas		100

COMPANY NAME	JURISDICTION UNDER WHICH ORGANISED	OWNERSHIP INTEREST
Non-US
MindShare Argentina S.A.	Argentina		100
M Media Group Pty Ltd	Australia		62
Mediacom Australia Pty Limited	Australia		62
Ogilvy Australia Pty Ltd	Australia		62
OPR AGENCY PTY LIMITED	Australia		62
Wavemaker Australia Pty Ltd	Australia		62
WPP AUNZ LIMITED	Australia		62
MediaCom – die Kommunikationsagentur GmbH	Austria		80
J Walter Thompson Middle East and North Africa E.C.	Bahrain		68
J Walter Thompson Publicidade Ltda	Brazil		100
KANTAR IBOPE Participações Ltda.	Brazil		100
KANTAR IBOPE Pesquisa de Mídia Ltda.	Brazil		100
Maristela Mafei Participações S.A.	Brazil		78
Ogilvy & Mather Brasil Comunicação Ltda	Brazil		100
PTR Brasil Publicidade Ltda.	Brazil		100
Y&R Propaganda Ltda	Brazil		90
Blast Radius Inc.	Canada		100
Entreprise de Communications Tank Inc.	Canada		100
John Street Inc	Canada		100
Mediacom Canada	Canada		100
MindShare Canada	Canada		100
Wavemaker Canada ULC	Canada		100
WPP Group Canada Finance, Inc.	Canada		100
Always (Shanghai) Marketing Services Co Ltd	China		65
Beijing Benpao Century Technology Development Co.,Ltd.	China		100
Blue Hive Shanghai Advertising Co Ltd	China		100
GroupM (Shanghai) Advertising Co. Ltd	China		100
Guangzhou Dawson Marketing Communication Co. Ltd	China		51
J.Walter Thompson Bridge Advertising Co. Ltd.	China		100
Kantar China Limited	China		95
Kinetic Advertising (Shanghai) Co. Ltd	China		100
Shanghai Easycom Advertising Co., Ltd.	China		75
Shanghai Linjie Marketing Services Co. Ltd.	China		70
Shanghai Ogilvy & Mather Advertising Ltd	China		100
TNS Sinotrust Market Research Consulting (Beijing) Co. Ltd.	China		100
Wavemaker Czech s.r.o.	Czech Republic		100
AKQA Denmark A/S	Denmark		75
MediaCom Danmark A/S	Denmark		100
Techedge ApS	Denmark		59
WPP Holding Denmark A/S	Denmark		100
Wunderman A/S	Denmark		51
CT Finances SA	France		83
Kantar SAS	France		100
Kantar TNS-MB SAS	France		100
KR Wavemaker SAS	France		100
Media Insight SNC	France		100
Mediacom Paris SA	France		100
Ogilvy & Mather S.A.S	France		100
Regional Management Group SAS	France		100
WPP Finance SA	France		100
AKQA GmbH	Germany		100
Commarco GmbH 120274	Germany		100
EMNID Gesellschaft mit beschränkter Haftung	Germany		100
GREY Düsseldorf GmbH	Germany		100
GroupM Competence Center GmbH	Germany		100
Groupm Germany GmbH	Germany		100
HERING SCHUPPENER Consulting Strategieberatung für Kommunikation GmbH	Germany		56
Hirschen Group GmbH	Germany		49
Kantar Deutschland GmbH	Germany		100
Kantar Live GmbH	Germany		100
Mather Direct GmbH	Germany		100
MediaCom Agentur für Media-Beratung GmbH	Germany		100
MediaCom TWENTYFIVE GmbH	Germany		100
MindShare GmbH	Germany		100
Ogilvy GmbH	Germany		100
PATH GmbH	Germany		100
plista GmbH	Germany		100
Syzygy AG	Germany		50
thjnk ag	Germany		100
Wavemaker GMBH	Germany		100
WPP Deutschland Holding GmbH & Co. KG	Germany		100
WPP Marketing Communications Germany GmbH	Germany		100
Young & Rubicam Group Germany GmbH	Germany		100
BATES CHINA LIMITED	Hong Kong		100
GroupM Limited	Hong Kong		100
MindShare Hong Kong Limited	Hong Kong		100
Wavemaker Hong Kong Limited	Hong Kong		100
WPP Marketing Communications (Hong Kong) Limited	Hong Kong		100
Wavemaker Hungary Kft	Hungary		100
AnalyticsQuotient Services India Private Limited	India		100
GroupM Media India Pvt Ltd	India		70
Hindustan Thompson Associates Private Limited	India		74
Kantar Analytics India Private Limited	India		100
MediaCom Communications Pvt Ltd	India		74
Ogilvy & Mather Pvt Limited	India		74
Ogilvy & Mather Pvt Ltd	India		74
FAST—Financial Administration Solutions & Technologies Srl	Italy		100
GroupM Srl	Italy		100
Mediacom Italia Srl	Italy		100
Mindshare SpA	Italy		100
Sentrix Global Health Communications Srl	Italy		100

COMPANY NAME	JURISDICTION UNDER WHICH ORGANISED	OWNERSHIP INTEREST
Wavemaker Italia S.r.l.	Italy		100
Xtel Srl	Italy		100
Grey Worldwide Inc (Japan)	Japan		100
WPP Scangroup Limited	Kenya		56
WPP Luxembourg Gamma Three Sarl	Luxembourg		100
WPP Luxembourg Sarl	Luxembourg		100
WPP Luxembourg Turris S.à r.l.	Luxembourg		100
WPP Marketing Communications (Malaysia) Sdn Bhd	Malaysia		100
MindShare de México, S.A. de C.V.	Mexico		100
Mirum, S.A. de C.V.	Mexico		100
Wavemaker Mexico, S. de R.L. de C.V.	Mexico		100
Worldwide Mediacom México, S.A. de C.V.	Mexico		100
WPP México, S.R.L. de C.V.	Mexico		100
Cavendish Square Holding BV	Netherlands		100
EffectiveBrands Holding B.V.	Netherlands		100
GroupM B.V.	Netherlands		100
Lightspeed Research B.V.	Netherlands		100
Russell Square Holding BV	Netherlands		100
Taylor Nelson Sofres BV	Netherlands		100
Wavemaker BV	Netherlands		100
Witgoud Investments B.V.	Netherlands		100
WPP Square one B.V	Netherlands		100
MediaCom AS (Norway)	Norway		100
GroupM Pakistan (Private) Ltd	Pakistan		100
Memac Ogilvy & Mather Holding Inc.	Panama		60
Kantar Philippines, Inc.	Philippines		99
Kantar Polska S.A.	Poland		100
MediaCom—Warszawa Sp.z.o.o.	Poland		100
MindShare Polska Sp. z.o.o.	Poland		100
Wavemaker Sp.z.o.o	Poland		100
Wavemaker Servicos Publicitarios Ltda.	Portugal		100
dtSI Inc	Republic of Korea		100
Kantar Korea Ltd	Republic of Korea		100
LLC ‘GroupM’	Russia		100
LLC ‘Mindshare’	Russia		100
LLC ‘Wavemaker’	Russia		100
GroupM Singapore Pte Ltd	Singapore		100
Ogilvy Singapore Pte. Ltd.	Singapore		100
Kantar South Africa (Pty) Limited	South Africa		81
Mindshare South Africa (Gauteng) (Proprietary) Limited	South Africa		79
Wavemaker (Pty) Ltd	South Africa		83
Kantar Media S.A.	Spain		100
Mediacom Iberia SA	Spain		100
Mindshare Spain SA	Spain		100
The Cocktail Global, S.L.	Spain		80
Wavemaker Publicidad Spain S.L.	Spain		100
WPP Holdings Spain, S.L.	Spain		100
Mediacom AG	Switzerland		100
Wavemaker Taiwan Ltd	Taiwan		100
WPP (Thailand) Ltd	Thailand		100
Mindshare Medya Hizmetleri A.S.	Turkey		100
Wavemaker MENA FZ LLC	United Arab Emirates		69
2Sixty Technologies Limited	United Kingdom		100
AKQA Limited	United Kingdom		100
Beaumont Square	United Kingdom		100
Cockpit Holdings Limited	United Kingdom		100
Cordiant Communications Group Limited	United Kingdom		100
Design Bridge Limited	United Kingdom		100
Enduring Organisation	United Kingdom		100
Essence Global Group Limited	United Kingdom		100
Finecast Limited	United Kingdom		100
G2 Branding and Design Limited	United Kingdom		100
Grey Advertising Limited	United Kingdom		100
GroupM UK Digital Limited	United Kingdom		100
Hill & Knowlton Limited	United Kingdom		100
Hogarth Worldwide Limited	United Kingdom		100
J. Walter Thompson Group Limited	United Kingdom		100
Kantar Media UK Ltd	United Kingdom		100
Kantar Retail UK Limited	United Kingdom		100
Kantar UK Limited	United Kingdom		100
Kinetic Worldwide Limited	United Kingdom		100
KR Media UK Limited	United Kingdom		100
Lightspeed Research Ltd	United Kingdom		100
Maxus Communications (UK) Limited	United Kingdom		100
MediaCom Group Limited	United Kingdom		100
Mediacom North Limited	United Kingdom		100
Mediaedge:CIA Worldwide Limited	United Kingdom		100
Millward Brown UK Limited	United Kingdom		100
Mindshare Media UK Limited	United Kingdom		100
Motion Content Group Limited	United Kingdom		100
MSIX Communications Limited	United Kingdom		50
Ogilvy & Mather Group (Holdings) Limited	United Kingdom		100
Precise Media Monitoring Limited	United Kingdom		100
Salmon Limited	United Kingdom		100
Spafax Airline Network Limited	United Kingdom		100
Stickleback Limited	United Kingdom		100
Superunion Limited	United Kingdom		100
The Finsbury Group Limited	United Kingdom		75
The Kantar Group Limited	United Kingdom		100
The&Partners London Limited	United Kingdom		50
TNS Group Holdings Limited	United Kingdom		100
Wavemaker Global Limited	United Kingdom		100
Wavemaker Limited	United Kingdom		100
WPP 2005 Limited	United Kingdom		100
WPP AMC Holdings	United Kingdom		100
WPP Beans Limited	United Kingdom		100
WPP Brands (UK) Limited	United Kingdom		100
WPP Brands Development Holdings (UK) Limited	United Kingdom		100
WPP Brands Holdings (UK) Limited	United Kingdom		100
WPP Finance 2010	United Kingdom		100
WPP Finance 2015 Limited	United Kingdom		100

COMPANY NAME	JURISDICTION UNDER WHICH ORGANISED	OWNERSHIP INTEREST
WPP Finance Co. Limited	United Kingdom		100
WPP Group (UK) Ltd	United Kingdom		100
WPP Jubilee Limited	United Kingdom		100
WPP Ottawa Ltd	United Kingdom		100
WPP Samson Limited	United Kingdom		100
WPP Sigma Limited	United Kingdom		100
WPP Sparkle Limited	United Kingdom		100
WPP Sphinx Limited	United Kingdom		100
WPP UK Germany Holdings	United Kingdom		100
WPP Unicorn Limited	United Kingdom		100
WPP Media Ltd	Vietnam		99