For non-UK residents and non-medical professionals, UCLH is the academic hospital system attached to University College London (UCL). It is generally regarded as one of the top 3-4 cancer NHS medical services in the entire UK (with others such as Marsden, KCL, and Oxford). Their GBM service in particular is the preeminent quaternary in the SE UK. Many if not most GBM suspected patients are referred to the MDT at UCLH for definitive diagnosis and treatment planning.
I appreciate how preeminent Prof Mrs Liau (as styled in UK terms) is in US medical circles. However, I would not sniff at a distinguished Uk oncologist and co-lead author from UCLH presenting on her behalf.