Mark is described in Chambers and Partners and the Legal 500 as “outstandingly clever”, “incredibly bright”, “a tenacious fighter”, “practical and commercial”, and “a marvel”. He "has a remarkable gift for predicting what judges will say and do”, and is “fantastically good on the technical side as well as being great at the client facing”. His “grasp of property valuations and their methodology is second to none.”
Mark practises in all areas of commercial and residential landlord and tenant and property law, but has particular expertise in the following:
- Development agreements
- Rent review
- Valuation disputes
- Overage
- Leasehold enfranchisement
- Options
- Contractual interpretation
- Dilapidations
- Lease renewals under Part II of the Landlord and Tenant Act 1954
- Easements and rights to light
- Sale and purchase agreements
- Property-related insolvency
- Complex commercial transactions
- Injunctions against protesters
In recent years, Mark has been instructed in a series of multi-billion pound valuation arbitrations concerning the largest residential property portfolio in England and Wales. He acted in the largest-ever open market rent review in Hong Kong, about a logistics facility in the Kwai Chung container port. He was instructed in the Supreme Court in the leading case on implied terms in contracts, Marks and Spencer v BNP Paribas, and he has appeared in both the Supreme Court and in the House of Lords in cases about leasehold enfranchisement. Before taking silk, he was the Real Estate Junior of the Year at the Chambers and Partners Bar Awards. Mark accepts instructions to act as a legal assessor and as an arbitrator, and he is widely recognised as having particular skill in disputes about valuation.
"Mark is an outstanding strategist and advocate of the highest calibre. He demonstrated a rare ability to cut through vast volumes of complex material and distil the case to its core principles with exceptional clarity. His strategic vision ensured that the argument remained tightly focused on the issues that truly mattered."Chambers and Partners UK Bar Guide 2027 (Real Estate Litigation)
"Mark is one of our go-to KCs for all types of commercial landlord and tenant issues, and his insights on valuation issues are particularly helpful. He is excellent with clients, and his advice is always clear and considered."Chambers and Partners UK Bar Guide 2027 (Real Estate Litigation)
"He's exceptionally commercial; having Mark in your corner really makes a big difference. When all hopes are lost he comes up with clever alternative ways of looking at things. He definitely has court craft and presence; when he starts speaking people listen. When he's on his feet, there's an electric buzz when he stands up."Chambers and Partners UK Bar Guide 2027 (Real Estate Litigation)
"Mark is excellent on valuation issues - he has significant experience and knowledge in this area. A brilliant advocate." Legal 500 UK Bar Guide 2027 (Valuation and Rating)
"Mark has exceptional clarity of vision and the ability to make complicated concepts as simple as possible for both clients and the Court. He is also clear in terms of his conclusions and does not tend to 'fence sit,' which is a quality that is highly regarded by our clients. His advocacy is clear and to the point, again with an admirable ability to make coherent arguments out of the most complicated issues."Legal 500 UK Bar Guide 2027 (Property Litigation)
"Mark is a real heavyweight to have in your corner." Chambers and Partners UK Bar Guide 2026 (Real Estate Litigation)
"He has an exceptional ability at cutting through complex and technical issues and articulating them in his submissions in a persuasive and succinct manner." Chambers and Partners UK Bar Guide 2026 (Real Estate Litigation)
"Mark is brilliant at explaining complex issues in a clear way." Chambers and Partners UK Bar Guide 2026 (Real Estate Litigation)
"Mark Sefton KC is a skilled advocate whose practice concentrates on commercial and residential landlord and tenant disputes, including high-value dilapidations cases. He excels in complex issues of valuation."Chambers and Partners UK Bar Guide 2025 (Real Estate Litigation)
"Mark is an exceptionally good technical barrister who is absolutely brilliant getting on top of conceptual points he comes up against."Chambers and Partners UK Bar Guide 2025 (Real Estate Litigation)
"Mark is switched on, bright, personable and a really nice guy overall."Chambers and Partners UK Bar Guide 2025 (Real Estate Litigation)
"Mark is a great communicator who is very good with clients due to his user-friendliness."Chambers and Partners UK Bar Guide 2025 (Real Estate Litigation)
"Mark is a great trial barrister who is very good at advocacy, including cross-examination."Chambers and Partners UK Bar Guide 2025 (Real Estate Litigation)
"A KC with excellent tactical nous."Legal 500 UK Bar Guide 2025
"Excellent on valuation-related work. Has significant experience of complex valuation matters."Legal 500 UK Bar Guide 2025
"Mark Sefton is a very effective advocate."
"Mark is commercially astute and great with clients and managing risk factors. One of the genuine leaders in his field."
"My first choice on any matters of interpretation."
"He has a clarity of thought that comes across in everything that he does, especially in his written work."Chambers and Partners UK Bar Guide 2024 (Real Estate Litigation)
‘Mark has excellent analytical skills and is able to assimilate and digest complex facts very quickly and then to apply the law to them. He is clear, concise and consistent in his advice.’Legal 500 UK Bar Guide 2024More published comments
