Tom Mallalieu is a senior associate in the Corporate & Securities practice of the London office. He joined Mayer Brown in 2019 from another international law firm. Tom’s core practice is advising on M&A in the upstream oil and gas sector across the globe, with a particular focus on the UKCS, Russia and North and sub-Saharan Africa.

Tom’s practice also includes advising clients on a wide range of commercial matters in relation to their upstream businesses. This includes joint ventures (JOAs, UOAs, shareholders’ agreements); advising in respect of agreements with host governments such as Licences, Concessions, PSAs and PSCs; drafting and negotiating upstream contracts such as DSAs, TPAs, CTIAs and product sales agreements; and involvement in financings, disputes and restructurings in the sector.


Prior to joining Mayer Brown, Tom’s career highlights include advising:


  • Europe
    • A European major on its multi-$billion purchase of a stake a super-giant Russian gas field.
    • A supermajor on the sale of its interests in several later-life assets and related infrastructure on the UKCS (including complex asset-backed security and ‘market-first’ retained decommissioning cost mechanics).
    • A private investor on the purchase of an offshore oil & gas group with substantial interests in Russia.
    • A supermajor on its sale of UKCS infrastructure, including several key offshore pipelines.
    • A US-owned company on its divestment of a stake in a major new UK gas storage project.
  • Middle East & Africa
    • A supermajor on its purchase of a stake in a significant gas development project offshore Egypt.
    • A European oil & gas company on its entry into a new offshore gas Concession, Abu Dhabi.
    • A UAE-based major on its purchase of interests in Kurdistan, Iraq.
    • A two-party consortium in their farm-in to two exploration Blocks, offshore Angola.
    • A UK-based explorer with the acquisition of assets in Gabon.
    • A Swedish company with its farm-out of interests in Congo (Brazzaville).
    • A supermajor with its market entry and farm-in to three exploration blocks, offshore Morocco.
  • Rest of the world
    • A European major on its farm-out of significant interests in Nicaragua and Colombia.
    • A Malaysian shipbuilder and service company with its sale of a minority stake in several ship owning companies to a Russian partner.
    • A UK-based E&P company with its farmout of two blocks onshore Colombia.
    • A South American company with its sale of a FPSO to a US-based investor.

General Corporate / Commercial

  • An oil & gas service company on a new JV relationship with a PE-backed oil & gas explorer, including a novel “synthetic equity” remuneration model.
  • A UK major on its first strategic alliance with a US-based oilfield contractor.
  • Several European majors on their UKCS operations: including in respect of new pipeline tie-in arrangements, DSAs, fuel supply agreements and product sales.
  • A European major on its proposed LNG terminal construction project (and throughput and LNG sales arrangements) in East Africa.
  • A Norwegian company on the restructuring and related refinancing of its UK production portfolio.
  • A US-hedge fund on its investment into asset backed oil company debt instruments.


  • England und Wales