Leon’s areas of expertise include market design, competition policy and the economic regulation of utilities. He is a member of the Regulation, Water and Competition teams at Oxera, and has particular expertise in incentive regulation, behavioural economics, industrial organisation and econometric analysis.

Leon has in-depth knowledge of the water sector, having been actively involved in all aspects of the 1999, 2004, 2009, 2014 and 2019 periodic reviews. Across utility sectors, Leon has detailed knowledge of incentive regulation, regulatory reform and market reform. He has worked for several small-island jurisdictions on regulatory change. He also has intimate knowledge of competition policy issues in utilities.

Leon has also undertaken a number of projects on consumer behaviour, firm behaviour and market design. He advised the UK Financial Conduct Authority as part of an economic experiment to investigate consumer decisions to shop around. He also advised the Netherlands Authority for Consumers and Markets on the impact of behavioural economics on competition policy in financial services.

Selected project experience

  • Advice on regulatory regime change to Águas de Portugal (2019)
  • Adviser on a behavioural experiment with Nottingham University for the UK Department for Transport (2019)
  • Expert witness, appointed by Manchester Ship Canal Company, on scheme selection and funding in the water sector (2017–18)
  • Advice to South West Water (UK) on PR19 regulation issues (2016–18)
  • Advice to the Canal & River Trust (UK) on water pricing principles (2017–18)
  • Advice to ComReg (Ireland) on setting financial penalties for breaches of regulatory obligations in telecoms (2016–18)
  • Due diligence advice to an investor on the impact of regulatory and market reform in the England and Wales water sector (2016)
  • Online economic experiment for the UK Financial Conduct Authority one the behavioural economics of consumer decision-making (2015–16)
  • Econometric analysis of the impact of the BBC on ITV audience, for the UK Department for Culture, Media & Sport (2015–16)
  • Managed a project on information quality incentives (IQI) for various UK electricity distribution companies as part of a CMA investigation (2015)
  • Managed a project on upstream access pricing reform for Severn Trent, a UK water company (2015)
  • Advice to a small-island economy on options for telecommunications ownership and regulation (2015)
  • Provided advice on best practice in privatisation and regulation, on behalf of Tallinn Water, Estonia (2015)
  • Provided training to various UK financial services providers and public bodies on the impact of behavioural economics (2014–15)
  • Advice to OpenWater on the options for establishing a market operator in the England water sector (2014)
  • Provided advice to an England and Wales water company on competition policy issues regarding default retail tariffs (2014)
  • Advised a public-sector infrastructure provider on incentivising performance (2014)
  • Provided advice to Redes Energéticas Nacionais (REN) on options for the regulation of electricity transmission in Portugal (2014)
  • Advised Federutility (Italy) on incentivising service performance (2013)
  • Provided bespoke training for Water Industry Commission for Scotland (WICS) staff on utility regulation and competition issues (2012–17)
  • Advised the Netherlands Authority for Consumers and Markets (ACM) on the impact of behavioural economics on competition policy in financial services (2012)
  • Advised Ofwat on incentives for network optimisation and for outcomes as part of its Future Price Limits project (2012)
  • Advised a large UK water company on access pricing issues (2012)
  • Assisted in examining the implications, from a behavioural economics perspective, of potential retail energy market reforms being proposed in the UK (2012)
  • Provided advice to the Turks and Caicos Islands government (TCIG) on the appropriate design of electricity regulation (2012)
  • Provided advice to the NMa (now ACM) on the role of buyer power in regulated transportation sectors in the Netherlands (2011)
  • Provided advice to the Isle of Man government on gas regulation (2011)
  • Managed and ran a training course for all Ofwat staff on the principles of utility regulation and competition policy, as applied across different utility sectors (2010)
  • Produced a report on the influences of behavioural economics and psychology on consumer behaviour, competition in markets, and in designing interventions (2010)
  • Advised the UK Association of British Insurers as part of a report on the effects of a potential ban on the use of gender in motor, health and life insurance pricing (2010)
  • Advised WICS on its reform of the regulatory system and incentives (2010)
  • Supported the Environment Agency in its assessment of different market and non-market approaches to water resources in the south-east of England (2009)
  • Advised a large water company in England and Wales as part of the PR09 review, through strategic advice and more technical advice (2009)

Selected publications

  • Niels, G., Dijk, R. van and Fields, L. (2013), ‘Behavioural economics and its impact on competition policy: A practical assessment’, Competition Law Journal, 12:3, pp. 374–84.
  • Fields, L., Horncastle, A. and Noble, R. (2009), ‘Water competition and the Cave Review: a clear way forward?’, Competition Law Journal, 8:3, pp. 238–47.
  • Fields, L. and Arias, L. (2008), ‘On the waterfront: will changing the rules deliver effective competition in the water sector?’, Competition Law Insight, 7:12, 9 December.


  • MSc Economics, University of Warwick, UK
  • BSc Economics, University of Warwick, UK