Bill is a Partner in the Commercial Disputes team. He specialises in heavyweight disputes. He has particular expertise in the management and resolution of major project disputes, claims arising from the sale and purchase of businesses, procurement challenges and the resolution of large scale business-critical supply/JV disputes.

Bill has an enviable track record of success in disputes and arbitration, together with all forms of alternative dispute resolution (ADR), including expert determination, negotiation and mediation.

He acts for national and international clients in a wide range of fields and has considerable experience of advising both private and public bodies in a range of sectors, including transport, health, utilities, retail and technology.

Bill's experince includes:

  • advising private and public sector organisations on complex and/or critical issues, including the management, re-negotiation, default and termination of major contractual relationships
  • assisting clients operating within both national and global supply chains on a range of issues, ranging from multi-million pound warehousing and distribution project turnarounds to breaches concerning critical component/materials
  • supporting suppliers and customer organisations on resolving large scale IT and outsourcing disputes, often relating to changes in specification/scope, project delivery delays and performance failures, using escalated dispute resolution processes, negotiation, mediation, expert determination, arbitration and Court proceedings
  • acting for a wide variety of contracting authorities and utilities, as well as bidder clients, on procurement challenges and achieving successful outcomes, by way of negotiation, strike out/summary judgment and swift partial re-run. Also advising "behind the scenes" on highly sensitive procurement issues.  Recent matters include advising as lead law firm to the Department for Transport in the 2019 Rail Franchising Litigation and advising HS2 in its dispute with Bechtel, with entirely successful judgments in 2020 and 2021 respectively
  • advising private and public sector organisations on complex and/or critical issues, including the management, re-negotiation, default and termination of major contractual relationships
Professional memberships
  • The Society for Computers and Law

"Bill Gilliam's sector knowledge is really useful - he has commercial awareness and business acumen."

"He is a creative legal thinker and brings forth good ideas."

Chambers 2021

"Bill Gilliam is the best solicitor that I have ever worked with.  He has first class judgement, provides great leadership to his teams, deploys his knowledge of the law and the commercial needs of his client to great tactical effect and is a pleasure to work with."

Legal 500 2021

"Bill Gilliam is a highly respected commercial litigator, known for representing major corporate clients in relation to contractual disputes, including supply chain issues. He also handles shareholder disputes. 'He provides a common-sense view of complex matters,' a client says, adding: 'His ability to understand the situation and tune in to the detailed nature of any legal matter is very impressive."

Chambers 2020

"Bill Gilliam is a very impressive partner in commercial litigation."

"Bill Gilliam is a market leader with detailed knowledge of procurement law in particular and a pleasure to work with."

Legal 500 2020

"Sources hold Bill Gilliam in high regard, stating that 'he gives clear legal advice and is willing to go the extra mile for the client', further noting that he is 'a very good strategist'. He represents a range of high-profile clients in varied commercial litigation and is particularly highlighted for his expertise in IT disputes."

Chambers 2019

"Bill Gilliam is a stand-out solicitor - a fantastic technical lawyer but also commercial and practical."

Legal 500 2019