Professional Negligence
Colleen has a broad professional negligence practice, including claims involving accountants and financial professionals, construction professionals, insurance brokers and agents, solicitors, and other professional service providers.
Colleen’s current and recent instructions in this area include:
Accountants and Financial Professionals
- Acting (during pupillage) for the promoter of a tax mitigation scheme in a claim concerning alleged failures to give adequate warnings as to the risk of the scheme being challenged by HMRC.
Construction Professionals
- Acting (led by Elizabeth Boon) for a professional indemnity insurer in a £1m claim under the Third Parties (Rights against Insurers) Act 2010 arising from alleged negligence by architects and surveyors in the design and contract administration of substantial residential works.
- Acting for a structural engineer in a claim concerning allegedly negligent design and engineering advice for a new-build property, following the discovery of cracking to the roof eaves.
- Acting for a firm of surveyors in a claim arising from allegedly inaccurate measurements of a residential property, said to have caused defects in the design of a loft conversion and consequential construction and diminution-in-value losses.
- Acting for a firm of architects in a claim alleging breach of contract and professional negligence arising from an alleged failure to submit a planning application before legislative changes came into force which increased the client’s costs.
Insurance Brokers and Agents
- Acting (led by Carlo Taczalski) for an insurance broker in a €40 million claim concerning the issue of surety bonds for construction projects. The broker is alleged to have issued bonds without authority, adequate due diligence, or sufficient collateral, and to have failed properly to manage the bonds and associated calls.
- Assisting a team of counsel acting for the claimant in a £15 million claim arising from the fraudulent placement of a non-existent reinsurance policy, including in relation to disclosure. Colleen also worked on the matter during pupillage.
Solicitors
- Acting for an insurer in a potential professional negligence claim against its former solicitors arising from an alleged failure to identify a contractual limitation clause, resulting in the loss of a substantial underlying claim against a construction consultant.
- Acting for a firm of solicitors in a claim brought by a real estate company concerning an alleged failure to pursue a Part 20 claim against its managing agent in underlying six-figure proceedings concerning breach of a repairing covenant.
- Acting for a firm of solicitors in a claim concerning an alleged loss of chance to purchase land from a local authority following a failure to advise on the time limit for judicial review proceedings.
- Acting for a firm of solicitors in a claim alleging negligent conveyancing advice concerning rights of way.
- Acting for a firm of solicitors in a claim alleging negligent management of personal injury proceedings, resulting in the underlying claim being struck out.
- Acting for a firm of solicitors in a claim arising from alleged negligent advice and representation in divorce proceedings.
- Acting for a firm of solicitors in a claim arising from alleged negligent advice and representation in criminal and custody proceedings.
Other Professional Service Providers
- Acting for a managing letting agent in a claim alleging failures in the drafting and enforcement of a guarantor agreement, said to have prevented recovery of unpaid rent from the tenant’s guarantor.
- Acting for a letting agent in a claim alleging negligent tenant referencing and failures to advise on rent protection, following the tenant’s default and abandonment of the property.
Selected Cases
View full profile »Awards
- Inns of Court Pegasus Scholarship
- Inner Temple Duke of Edinburgh Entrance Award
- Inner Temple Major Scholarship
- Inner Temple Exhibition Scholarship
- Dean’s Award for Best Academic Performance in MA Law (Conversion)
- Various Finals Collections Prizes from Oriel College, University of Oxford
- Winner of Multiple Moots / Mock Trials incl. the Aqeel H. Noorali Moot Cup
News
- Crown Office Chambers to attend the Bar Council’s Pupillage Fair, 17 October 2026
- Hamish Fraser and Colleen Cumbers recognised in the Pro Bono Recognition List 2026
Articles
Blogs
Events
- Crown Office Chambers to attend the Bar Council’s Pupillage Fair, 17 October 2026
- Crown Office Chambers at The National Pupillage Fair 2024
Qualifications
- BA French and German (First Class), University of Oxford
- MA Law (Conversion) (Distinction), University of Law
- LLM Master of Laws (Distinction), University of Law
Memberships
- Commercial Bar Association (COMBAR)
- Technology and Construction Bar Association (TECBAR)
- The Society of Construction Law (SCL)
- Professional Negligence Bar Association (PNBA)
- London Common Law & Commercial Bar Association (LCLCBA)
- Young International Arbitration Group (YIAG)
- Personal Injury Bar Association (PIBA)
