Our executive
Our Executive team is responsible for the day-to-day running of the business and is made up of the Chief Executive, Chief Financial Officer (CFO), and seven functional directors.
Sarah Bentley - CEO

Chief Executive Officer - Thames Water Utilities Limited
Appointed: September 2020
Relevant skills:
- Multi-disciplinary executive with extensive water industry experience, strong operational leadership of large service-oriented workforces and track record of developing strategy and delivering transformational change.
- Relentless customer focus, deep expertise in digital technology and passionate about delivering results through the creation of diverse and high performing teams.
Relevant experience:
Sarah joined Thames Water as Chief Executive Officer in September 2020. Previously, Sarah was on the Executive Committee at Severn Trent plc where she was appointed as Chief Customer Officer in 2014, leading the Consumer Retail, Wholesale Network Operations, Group Technology and Transformation divisions. She is also a Non-Executive Director of Lloyds Bank plc and Bank of Scotland plc.
Before Severn Trent, Sarah was the managing partner for Accenture’s digital business unit in the UK & Ireland delivering digital transformation programs to a range of large UK consumer-facing businesses and was a member of the Accenture UK & Ireland Executive Committee. Prior to Accenture, Sarah worked internationally in a number of roles including strategy, marketing and propositions for BT’s Global Services division, CEO of Datapoint, an Alchemy-backed company delivering customer relationship management (CRM) services throughout Europe, and senior vice president of eLoyalty, a global CRM and marketing consultancy. She was SVP of the European business, led the sales and operations activity in North America and ran eLoyalty Ventures L.L.C. working in Silicon Valley, Austin and New York.
Sarah graduated from the University of Kent with a first-class honours degree in Management Science and Computing (BSc Hons) and is married with five children.
Brandon Rennet - CFO

Executive Director/Chief Financial Officer - Thames Water Utilities Limited
Appointed: March 2017
Relevant skills:
- Strong expertise in leading the execution of multi-billion-pound funding, primarily in the public debt capital markets and creating sustainable financing structures to support corporate sustainability aims
- Valuable utility experience combined with public policy exposure.
Relevant experience:
Brandon brings substantial financial leadership success to his role as Chief Financial Officer having spent three years of a ten-year tenure as Managing Director of Finance at regulated energy company, SSE Plc. While in post he led the execution of more than £7 billion of funding and initiated a finance transformation programme.
John Beaumont - Asset, Strategy and Planning Director

Appointed: September 2017
Relevant skills:
- Experience driving complex change in regulated companies.
- Proven background using digital technology to create customer obsessed businesses.
Relevant experience:
John directs asset strategy and planning with a focus on improving customer outcomes and reducing operating costs.
Prior to Thames Water he spent 12 years directing customer focused and operation-led transformations as a Partner at Bain & Company where he worked expansively in the digital and technology space across a variety of infrastructure-heavy industries. His early career was spent at Deloitte and PA Consulting.
John Bentley - Capital Delivery Director

Appointed: October 2019
Relevant skills:
- Experience of developing and implementing different operating models and bringing together people from multiple organisations to deliver investment needs.
- Shaped capital investment plans across three price reviews.
Relevant experience:
John is a chartered civil engineer and has 28 years of water industry experience working for Severn Trent Water. During this time, he managed £billion, complex capital investment programmes. As the Capital Delivery Director, John’s responsible for the safe and efficient delivery of AMP6 investment through the eight2O Alliance partners. He is leading the development of, and transition to, a new capital operating model which will secure more value for customers throughout AMP7.
Warren Buckley - Retail Director
Appointed: March 2021
Relevant skills
- Extensive experience in leading customer service and sales transformation across multiple industry sectors including Telecoms and Financial Services
- Over 30 years of people leadership and cultural change to create truly customer focussed teams including frontline experience having started as a call centre agent
- Proven background of integrating human and technology in delivering seamless digital and non-digital channels
Relevant Experience
Warren joins Thames Water from HSBC plc where he was responsible for the onshore and offshore contact centres for its Retail and Wealth business, including customer experience transformation and sales and service performance. Warren led a team of 27,000 colleagues globally for HSBC as their Managing Director and Global Head of Channel Optimisation and Contact Centres.
Prior to HSBC, Warren held several positions at BT including Managing Director of Customer Service and Operations at BT Retail, and Managing Director of Service Management at Openreach, having previously held customer service, experience and operational leadership roles at Orange, Avaya, Lucent Technologies and Vodafone.
Warren is also the Chair of Citizens Advice, a position he took up in 2018 having served as a trustee since 2012.
Nicola Cocks - Regulation Director

Appointed: October 2019
Relevant skills:
- Delivering high quality engagements, particularly focused on regulatory and economic analysis and project delivery.
- Wealth of experience within the utilities sector.
Relevant experience:
Nicola has over fifteen years of utility regulation experience. This includes ten years at the energy regulator Ofgem, where her roles included acting as Project Manager for some of Ofgem’s most critical and high profile projects. She spent five years at KPMG, as Director of Power and Utilities. This included acting as a strategic advisor to a number of UK leading network companies on their price control reviews, in providing regulatory insight and assistance to companies facing compliance and/or enforcement action from their regulator and in undertaking agreed-upon-procedure reviews of companies’ regulatory reporting prior to submission.
Nicola was Head of Projects and Programmes at Ofgem, transforming the capability and effectiveness of the business in delivering projects that achieved most value for Ofgem and for consumers.
Lynne Graham - Human Resources Director

Appointed: January 2020
Relevant skills:
- Experience in designing and delivering complex cultural and organisational change programmes.
- Skilled in leadership development; MSc in Coaching and Behaviour Change.
Relevant experience:
Lynne is accountable for the HR function, covering the entire employee life cycle including talent attraction and selection, reward and benefits, payroll and administration, learning and development, employee relations and organisational development.
She has led major change programmes that have delivered significant value through cost reduction and through productivity improvements by driving an engaged culture.
Prior to Thames Water she has operated at Executive and Main Board level in diverse sectors – Eurostar (rail); British Gas (gas utility); Westbury Street Holdings (hospitality); Yodel (logistics).
George Mayhew - Corporate Affairs Director

Appointed: August 2019
Relevant skills:
- Significant experience in corporate affairs.
- Proven background in stakeholder and government relations for organisations across a range of sectors.
Relevant experience:
Before joining Thames, George was Group Corporate Affairs Director at National Grid, where he was responsible for the company’s reputation and stakeholder management strategy. His role included policy development, government and media relations, employee communications, corporate responsibility and brand.
Prior to this, George was Chief of Staff to the CEO of BAE Systems for four years and previously held various government relations roles at MBDA Missile Systems, Centrica and Granada TV.
Steve Spencer - Operations Director

Appointed: April 2017
Relevant skills:
- Significant experience of the water industry over 25 years.
- Proven track record of improving performance and delivering strong operational results.
Relevant experience:
Steve oversees the efficient running of water and wastewater operations. He is responsible for delivering high quality drinking water and reducing leakage, alongside safely processing wastewater, transforming it into renewable power and returning clean water to our rivers.
His career has been dedicated to the water sector. Not only has he held senior leadership positions across Thames Water, he has also worked at Southern Water and MWH Australia.