21 May Day in the life A Day in the Life of a Japanese Knotweed Expert Expert evidence, Expert Witness, 01. Starting your Expert Witness Business, Japanese Knotweed, Invasive Species Week, Phlorum, Dr Paul Beckett, 14. Changing your opinion, 15. Giving Oral Evidence One of the UK’s leading experts in Japanese knotweed, Dr Paul Beckett has been providing Expert Witness services since the early 2000s. He shares his insights into being part of a relatively new area of litigation; what makes a good Expert Witness; and why he approaches court like revising for an exam.