What kind of speaking are you expecting to do in your viva?
Do you imagine you’ll have to explain what you did?
Do you think you’ll simply expand on what you’ve done?
Or perhaps you think you will explore what your research really means?
In truth: you’ll do all of these and more. The viva is a discussion centred on your research, your thesis and you. The conversation can go in many different directions. Expect that you’ll explain, expand on and explore a lot of what you’ve done.
Don’t expect that your examiners will expose big problems though – or explode your central ideas!