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:

  • Advising a European oil & gas company on its multi-$billion purchase of a stake a super-giant Russian gas field.
  • Advising 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).
  • Advising a supermajor on its purchase of a stake in a major gas development project offshore Egypt (including the negotiation of a new joint venture).
  • Advising a European oil & gas company on its entry into a new offshore gas Concession, Abu Dhabi.
  • Advising a European service company on a new JV relationship with a PE-backed oil & gas explorer, including a novel “synthetic equity” remuneration model.
  • Advising a European major on its purchase of an operated interest in a major new UKCS development project.
  • Advising a UAE-based major on its purchase of interests in Kurdistan, Iraq.
  • Advising a European major on its farmout of significant interests in Nicaragua and Colombia.
  • Advising a two-party consortium in their farmin to two exploration Blocks, offshore Angola (including the negotiation of two new joint ventures).


  • England and Wales