Lee O’Sullivan

Year of call:

2003 (Solicitor 2008)


2001 - University of Derby, BA (Hons) in International Law and Politics

2002 - University of Northumbria, Newcastle, Post-Graduate Diploma in Law

2003 - Inns of Court School of Law, London Bar Vocational Course, Very Competent


2003 - Assistant at Stewarts Solicitors, London

2005 - Assistant at Freshfields Bruckhaus Deringer, London

2008 - Associate Solicitor at Sprecher Grier Halberstam LLP, London

2010 - Managing Associate at Addleshaw Goddard LLP (Solicitor Advocate 2017)

Ranked in The Legal 500 (2024) for Commercial Litigation.

“Lee is a tenacious advocate – hard-working and dedicated. A very commercial junior” The Legal 500 (2023)

Having previously been in-house as a solicitor advocate at a large law firm, Lee accepts instructions a wide range of civil and commercial litigation matters.

Lee specialises in banking and financial services litigation, property litigation, claims concerning mortgages, competing interests in land, charges and security (including guarantees and indemnities), asset finance, professional negligence (particularly claims involving lawyers, expert witnesses, surveyors and valuers), product defects, consumer rights, and claims concerning the sale and supply of goods and services.

The Legal 500 UK 2019 Yorkshire & Humber named as a leading individual.  Highlighted as being “”extremely competent” particularly in complex banking matters”.

Examples of recent work

  • Successfully appeared in the High Court to oppose an application for relief from sanctions, permission to extend time to appeal, to amend the ground of appeal and to rely on fresh evidence.
  • Successfully appeared in a 3-day trial against leading counsel in a claim to enforce a number of finance lease agreements concerning two precision engineering machines.
  • Successfully appeared in the High Court and set aside an order granting a stay of execution pending determination of an appeal.
  • Successfully appeared in the County Court in an application for third party disclosure.
  • Successfully appeared in an application to strike out a defence and counterclaim in which it was alleged that an occupier’s interest took priority over a first legal charge.
  • Appeared in the High Court in an application for a civil restraint order.
  • Appeared in the High Court to oppose an application for an interim payment following the filing of a notice of discontinuance.
  • Successfully obtained an order for indemnity costs and the full enhanced measures in CPR Pt 36 where a defendant had failed to beat a claimant’s Part 36 Offer following trial.
  • Appeared in the County Court and obtained an order limiting the number of witnesses a defendant could rely on at trial.
  • Successfully appeared in the High Court to strike out a defence / obtain summary judgment in a claim against a partner in a law firm under his professional practice loan.
  • Successfully obtained a return of goods order in respect of farming equipment and machinery in a claim arising from a series of hire purchase agreements.
  • Settled Defence and Counterclaim in a claim against an asset finance company for breach of implied terms of satisfactory quality and fitness for purpose relating to a high value motor vehicle.
  • Settled Defence in a claim brought by insurers under subrogated rights in respect of a high value motor vehicle that set alight whilst being driven a public highway.
  • Advised a leading bank on thematic issues arising from its standard form personal guarantee and indemnity.

Notable case

Deutsche Leasing (UK) Ltd v (1) Zaskin College Ltd (2) Mr Kazmi [2018] EWHC 1977 (QB).  An appeal to the High Court in a case concerning the ‘date of decision’ for the purposes of calculating time for filing an appellant’s notice.  The case is of general interest because the appellant sought to assign blame on his solicitors for failing to file the appellant’s notice within the relevant 21 day period.  The case also provides an up to date example of the court’s approach to applications for relief from sanctions applications in such circumstances.

Professional Negligence

Lee has many years of experience of both prosecuting and defending claims against professionals.  Lee has a particular interest in claims against lawyers and surveyors.

Examples of work

  • Settling Defence to a claim against a valuation surveyor for failing to observe and advise on signs that were indicative of structural defects in a residential property.
  • Settling Particulars of Claim in a claim for breach of contract, negligence and breach of trust against the partners of firm of solicitors in respect of the conduct of 10 buy-to-let property transactions.
  • Settling Particulars of Claim in a £1.8m claim against a firm of solicitors for breach of trust and breach of fiduciary duty in respect of their conduct in 40 conveyancing transactions.
  • Advising a group of Yorkshire businessmen in respect of a claim against their financial advisor relating to a tax efficiency scheme operating in the Caribbean.
  • Settled Particulars of Claim in a £2m claim against a firm of solicitors that had failed to secure a first legal charges in a large number of conveyancing transactions.
  • Advised on the merits of a loss of profit claim against a firm of solicitors that had failed to act on instructions to exercise a break clause in a commercial lease.


“Lee is able to match the high standard of his written work with tenacious advocacy. I know when I instruct Lee that he will deliver exceptional attention to detail, a remarkable understanding of the legal framework and be able to apply both to the commercial reality for my clients. Lee and I have worked closely together on many court hearings which have resulted in success for my clients. This has included a three day hearing on a merchantable quality dispute, whereby Lee was acting against a QC, and my client was facing a £1m counterclaim. Lee was able to deliver a full victory for my client together with indemnity costs for the entire proceedings. I would not hesitate in recommending Lee to others.” – Instructing Solicitor, 2019

Prior Career

2008 to 2010: Associate Solicitor, Litigation, Sprecher Grier Halberstam LLP, 1 America Square, London acting for a range of national and international business and financial institutions in commercial & chancery litigation matters.

2010: Managing Associate, Litigation, Addleshaw Goddard LLP, 3 Sovereign Square, Sovereign Street.  Regularly instructed to act on behalf of major financial institutions, SME’s and FSTE companies.

In 2017, Lee became In-house Counsel undertaking a wide range of advocacy for the firm’s major clients where he was frequently instructed to appear at costs and case management conferences, applications for relief from sanctions, trial, appeals in the High Court and Court of Appeal, together with a range of interim applications, including strike out/summary judgment, disclosure, and return of goods.

Notable cases as a solicitor

  • National Westminster Bank Plc v Alfano & Ors [2012] EWHC 1020 (QB)
  • Alfano & Ors v National Westminster Bank Plc [2013] EWCA Civ 1703 (20 December 2013)
  • Anne Hubbard v Bank of Scotland Plc [2014] EWCA Civ 648
  • Mortgage Express Limited v (1) Awas Khan (2) Muhammed Yousaf [2017] EWHC 53 (Ch).

Contact Lee’s clerks

Senior Clerk – Andy Reeves on 0113 213 5252

Talia Webster on 0113 202 8609

Joshua Duree on 0113 213 5246

Mike Alexander on 0113 2135268

Ben Ellison-Tope on 0113 2135207

Legal 500 Leading individual 2019 The Legal 500 2017 leading individual logo