Jamie Mangan | Fieldfisher
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Professional background

Professional background

I have over 12 years' experience advising clients on a full range of contentious property disputes and other property matters. I act for and provide strategic support to developers, investors, occupiers, public sector bodies and high net worth individuals. My experience includes dilapidations, business lease renewals, break clauses, the recovery of arrears, tenant insolvency as well as real property issues including easements and covenants.

My practice also encompasses high value and complex rent review disputes. I regularly act on some of the most significant rent reviews in the market, or alternatively as the appointed legal assessor.

In addition to rent review, I have particular expertise in professional negligence, insolvency and rights of light. I have acted and continue to act for clients on claims against solicitors in respect of negligent drafting or reporting on property transactions, and against surveyors in respect of negligent valuation or transactions at an undervalue. On insolvency, I regularly advise landlord clients on the options available to them once a tenant enters into insolvency, and have particular experience advising on the effect of CVAs on the landlord and tenant relationship. On rights of light, I assist developer clients in devising strategies to ensure that developments can proceed without the threat of injunctive relief while also minimising risk and exposure to third parties as far as possible.

I am also very experienced in all forms of alternative dispute resolution including arbitration, expert determination and mediation.

My experience includes:

  • acting for the City of London in respect of the wholesale market relocation of Smithfield and Billingsgate to a new co-located market site at Dagenham Dock;
  • acting for various lender clients on a professional negligence claims against surveyors in connection with valuations they provided on properties for the purpose of secured lending;
  • acting on a complex claim (including allegations of professional negligence) against multiple defendants in connection with the alleged sale of two development sites at an undervalue;
  • obtaining a freezing injunction in the High Court in respect of a claim involving an alleged fraudulent misrepresentation in the sale of multiple apartments;
  • acting for a client on a contested lease renewal, where the client was successful in opposing the grant of the new lease under ground (g) of the Landlord and Tenant Act 1954; and
  • acting for an occupier client in opposing forfeiture of a highly valuable commercial lease and counter-claiming for relief from forfeiture in the alternative.

My rent review and related valuation experience includes:

  • acting on a high value and complex rent review arbitration in respect of a former industrial site in central London, involving extensive work with expert witnesses;
  • acting on a rent review dispute relating to a health centre in West London involving a complex legal issue relating to the interpretation of index-linked rent reviews;
  • acting on a rent review dispute in connection with an industrial property in Peterborough involving complex legal issues relating to the relevant comparable properties;
  • advising an arbitrator on a dispute as to his substantive jurisdiction in an arbitration relating to the purchase price payable under an option agreement; and
  • acting as legal assessor to an arbitrator in connection with a preliminary legal issue as to whether works to the property were to be disregarded on rent review.

I am frequently invited to speak at conferences on the topic of rent review, including the Arbrix Open Conference and a regular panel role at Surrey Arbrix.

I was recognised as a Leading Associate by Legal 500.

Awards & recognition

Awards & recognition

Legal 500 2024
A "standout individual" who is "incredible at both building friendships and providing practical solutions to quite often complex legal issues".
Legal 500 2024
Completely up-to-date and knowledgeable on landlord and tenant law.
Legal 500 2025
Jamie Mangan provides an excellent level of service and accessibility.
Legal 500 2025
The 'exceptional’ Jamie Mangan focuses on rent review work for leading clients.

Authored pieces

All Resources
A low-angle view of modern glass buildings reflecting colorful hues of pink, red, blue, and yellow under a clear sky. The structures create a geometric pattern with their intersecting lines and vibrant panels.
Real Estate
Insight

English Devolution and Community Empowerment Bill – the future for lease rent reviews?

15.07.2025
Up down/funky town With temperatures soaring last week, something other than the weather was making the property industry hot and bothered - the shock announcement that the Devolution Bill proposed a ban on upwards-only rent reviews in all new commercial leases in England and Wales (the "Proposal").
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Real Estate
Insight

Shining a light on the Sheffield Masonic principle, and other Rights of Light considerations

13.09.2024
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A low-angle view of a modern building with colorful, reflective glass panels. The vibrant sections of red, pink, blue, and yellow stand out against the clear sky, creating a visually striking and geometric pattern.
Insight

Dealing with the impact of Covid-19 in the commercial property sector

16.12.2020
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Stacks of coins are arranged on a surface with a digital overlay of financial graphs and charts in the background, suggesting themes of financial growth and analysis. The muted, cool-toned color palette adds a modern, abstract feel.
Insight

COVID-19 – Impact on rent review

26.03.2020
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What others say…

Legal 500 2024
Completely up-to-date and knowledgeable on landlord and tenant law.
Legal 500 2025
Jamie Mangan provides an excellent level of service and accessibility.
Legal 500 2025
The 'exceptional’ Jamie Mangan focuses on rent review work for leading clients.