I can't seem to quote Fastpiece's post #905.
But there are two postcards from Marion which mention her going to Amsterdam and she seems excited about it.
In yet another postcard, she mentions meeting a Dutch dentist and Mazz. Because MB mentions going to Winchester Cathedral, others have assumed she met them there. But it doesn't say that. IMO we cannot assume that MB met them there.
Because I predict that mentioning Amsterdam twice and the Dutch dentist, there could be some relevance to MB's fate.
It has been my theory for some time that RB has excited MB about the prospect of her visiting Amsterdam for the second time. He has probably told her that he will take her there. But he eventually tells her that he is too busy now or had had an accident, etc. to do that so he has asked his friend, the Dutch Dentist to accompany her as he will be visiting the UK with his friend, Mazz, later in July and RB tells MB that he has arranged an apartment in the south of England so that they can all be together to get to know each other before the trip. (one postcard was sent from Kent)
Marion cannot mention RB's friends to family on any postcards as she doesn't want them to know about RB (as he has instructed her) so she mentions Amsterdam and the Dutch dentist on three postcards so on her last postcard, she drops it in as if she just casually met them one day and that was it.
IMO MB was never informed that RB had flown back to Australia and he was the one who probably wrote the outgoing and incoming passenger cards forging her handwriting as he had collected them on a previous trip for this purpose. IMO he probably told MB that this was the story she had to tell on her outgoing passenger card so it was best for him to write it so she did what he said. He later booked the flight for Mazz and gave her the incoming passenger card to use so they would match both in handwriting and story.
It was then the Dutch dentist's job to give proof of life in England after RB flew back home by advising MB to phone Sally after RB left and writing the postcards stating in one she wouldn't be writing much as she'd be travelling which he posted later from Kent. His next job was to end MB's life and hide her body. I have also wondered whether this possible accomplice of RB's was the so-called travel agent he mentioned to JO.
Just trying to make possible connections between what we know. But IMO MB never got to go to Amsterdam. Her life ended in August, 1997.