Other people have said Julie was pressurised into writing a WS by the police.
This is incorrect. She approached the police via Liz Rimmington. The police had no idea about the caravan break in or Susan Battersbys 1984 cheque book fraud.
So Jeremy is right, there is only one reason for Julie to lie. But first people have to agree he did jilt her. And jilt her badly.
The supposed phone call she overheard was tacky but not the source of their breakup. They had already broken up by the time he asked out an old girlfriend in front of her. In this case it seems that the murders disturbed her to the point that their relationship broke down over it. She was in the process of saying goodbye when he called this other woman so that can't have been the source of the break up.
When peopel break up they sometimes do things to spite one another but is the the kind of person who would spite him by making up such a tale and would simply overhearing him flirt with another girl after they broke up warrant her to do something so severe?
The relevant inquiry is to look for corroboration and what makes sense.
They didn't have a bad breakup where one or the other instantly cut off contact with the other. It was a progression where they salw less of eachother over time and went separate ways but still said goodbye and still were together saying goodbye. This is not the situation where one says I never want to see you again and they simply cease all contact. Her explanation of the cooling down being because of she felt bad over the murders makes sense. No alternative explanation for the breakup was put forward by Jeremy. The claim the breakup was because he overheard the flirting is false, the flirting was after they broke up.
It doesn't make sense to lie about someone being involved in murders to get back at someone for flirting in her presence, but the most likely thing to make up in such circumstances would be to say he told her he did it. Not to say he told her a hitman did it and that he even gave the hit man's name. That is counter productive because police could instantly check if the alleged hitman has an alibi or not and thus could easily rule out the claim and it won't cause the desired harm. At minimum such a made up claim would not name a hitman and just claim an unspecified hitman. Again though the most common lie to tell in such circumstances would be tha the admitted he did it not ake up a hitman claim.
The level of detail she provides as far as the various times he talked about wanting to kill his faily is also significant. It is hard to make up such level of detail without a lot of thought and planning to come up with such. The claims are all credible not amazingly crazy claims. Her account seems credible.
There are details to corroborate her claims such as Ann Eaton saying her told her that he would be co-owner of the caravan site with her soon and the very details of the murder which point to Sheila not being the killer but rather someone else and that someoen else had to be Jeremy based on the made up phone call and fact he is the one who insisted it had to be Sheila.
A lot of things go into weighing credibility.
Her claims were part of the overall puzzle.