His principal research activities focus on Machine Learning and Cognitive Systems, for which he pioneered a number of approaches including the kernel neutral point and tomographic methods. He also has a former research interest in Astrophysics having obtained his PhD in Cosmology at the University of Bristol. His long-term interest in kernel methods and his prior background in physics converge naturally in his quantum machine learning research. David has authored 150+ papers and played a leading role in academic and industrial projects at the interface of machine learning and cognitive systems (including EPSRC ACASVA, EU DIPLECS and Dreams4Cars). He is a Visiting Academic at the Centre for Vision, Speech and Signal Processing (CVSSP) at the University of Surrey UK, and sits on the Editorial board of Springer Quantum Machine Intelligence.