I think it might well have been possible to repatriate the diary (I’ve done so before by detective work & ringing around, but maybe CV cut to chase by calling her bank). (chequebook with diary).Other than it was 'Screws of the World' material did he ever say what it was?
DL would have likely regarded her daughter as a slapper if she'd slept with one bloke, but this AS comment sounds like it might be about this area and like we might be talking a lot more than one.
If so, the police decision to give up inquiring into the contacts in the diary makes more sense. What if there were 300, for example?
It is also interesting that there was no way of working out who the diary belonged to - CV said there was no name / contact number in it. Who keeps a key diary with important contacts in it, but leaves no information in it that would allow someone to reunite you with it if you lost it?
The police gave up halfway through checking out the owners of the very definitive BMW seem in Shorrolds too, age/class etc, lack of resources I think.
IMO what was ‘kept back’ & the diary didn’t point directly to numerous lovers.
AS didn’t give any specific details.