Well, it happened this morning and I survived - thanks at-least partly due to the good advice of Ppruners.
Interestingly it was shorter than I'd expected - lasting about 90 minutes. The chairman started by asking me to summarise the research, which took me 20 minutes or so, then a little over an hour was spent on variously searching questions or in fact mainly requests to explain my methodologies and the design of the main aircraft I'd worked on. I was surprised that apart from my supervisor, the panel was almost totally unfamiliar with a lot of my published work - mind you that did give me a fair bit of moral high ground
Finally they gave me a stack of comments - mostly about the fact that my thesis read too like a technical report and not an academic thesis (given the day job, unsurprising and correctable) and asking for my final thesis for a stack of additional work to be included - much of which I've written elsewhere thankfully. Then they threw me out for half an hour, and finally my supervisor debriefed me over lunch.
Good news is that I've been recommended for transfer to the final PhD, the additional material needed all seems well within my capabilities, so once the summer flying season dies down a bit I'm setting myself the objective of getting my final thesis in the system by about christmas (I've had enough now and want to finish the job!).
It could be related to the fact that I hopefully know my subject well after working on it for 6 years or so - but I must admit I found that compared to my previous two benchmark nasty interviews - CEng and ETPS - it was surprisingly painless.
Right, onto the next bit...
G