While Dimbleby on Question Time often raises my hackles (sic) too, I think some of the nitpickers on this thread clearly have no concept of the pressures of live commentary and otherwise need to get a life.
We found the BBC programme very moving and have little confidence that any of the commercial broadcasters would have done it better.
No amount of homework will give a reporter the sort of encyclopaedic knowledge of the multifarious personalities and units (many now sadly extinct) that some here seem to expect.
Whatever our detailed knowledge of the part of the services we were part of, how many of us could identify facets of the others in the few seconds a TV camera allows?
The broadcaster has to cater for average uninformed viewers (the majority) as well as the vociferous specialists waiting to pounce on any slip up. In the future, however, the red button may be used more often to provide a commentary-free version.