Partner, Patent Attorney London
Profile of Catherine Mallalieu

I have been a partner at D Young & Co since 1997, and first represented clients before the European Patent Office (EPO) in 1991. I enjoy building long-term relationships with clients and helping them achieve their goals.

I am a highly experienced patent attorney working across both the chemical and biological sectors. I specialise in biotherapeutics, cell and gene therapy, gene editing, specialty chemicals, nutritional products and veterinary products, plus a range of related technologies. I have a thriving prosecution practice as well as a substantial EPO opposition and appeal portfolio.

Before joining D Young & Co, I gained valuable in-house patent experience at Zeneca Agrochemicals, where I was responsible for their bioscience and insecticide divisions. This role, combined with my subsequent work acting for major international organisations, has enabled me to develop a highly focused, commercial approach.

I also advise emerging companies and academic institutions on how to build value through their IP portfolio. This has often involved IP due diligence for mergers, project acquisitions and flotations.


  • BSc in Chemistry, University of Birmingham.
  • European Patent Attorney 1991.
  • Chartered Patent Attorney 1991.
  • European Design Attorney.


  • Chartered Institute of Patent Attorneys (CIPA).
  • CIPA Patents Committee.
  • European Patent Institute (epi).
  • European Patent Litigators Association (EPLIT).


  • Contributor to Chartered Institute of Patent Attorney’s European Patents Handbook.
Mallalieu is an incredibly experienced practitioner who is very successful at getting applications through to grant and upheld in opposition – a real star.
IAM Patent 1000
Highly recommended 2018.
Legal 500
She’s quick to understand her clients’ technologies and to recognise their business needs. On top of that, she’s always responsive to enquiries and works collaboratively with in-house IP managers and scientists to ensure that their innovations are appropriately protected.
IAM Patent 1000
An excellent understanding of clients’ commercial interests.
Legal 500
Catherine Mallalieu and Simon O’ Brien are very reliable and have excellent legal and scientific backgrounds.
Catherine Mallalieu garners praise for her work rate and clarity: “She is able to take on a lot of work and still respond quickly, giving clear opinions every time.”
IAM Patent 1000