I would hate to cast any nasturtiums on your dissertation "Rose", but, I think the reason that people like him are used is that they will pull in a wider, more diverse, viewership than one that has only fact and "specialist opinion" to offer. Personally the thought of watching an hour long programme on the Sea King, narrated by John Nicholson (Tornado Navigator) would ensure my TV never got near the channel. I agree with your thoughts on the BBC, but think that John Sarjent is a good choice to present a program which should give due respect to the aircraft and its crews, whilst, having a bit of banter to keep the non anoraks engaged.
Smudge