He could have approached them naively like he did AL and been sent a lawyer's letter saying if he should so much as mention them in any book he'd be sued silly and the book pulped. This could be well in advance of his developing any theory.
It would be suspicious in itself but it's been very successful. In the 40 years of books, articles and documentaries about this case they have not been mentioned once. Every such production goes straight from Shorrolds to Cannan without passing Go, collecting £200 or interrogating the case against him in any way at all. When did you ever see a TV doc that said here's why it doesn't fit Cannan?
I suspect a condition of police participation in these programmes is that the programme makers must conclude it was JC.
Interesting. But why - his theory has them nowhere near her abduction.
i wonder if dv had multiple theories but went with one that may get results