They don't just charge people on false claims like that. I can't go into detail but sadly a member of my family is currently going through the exact same thing, it took almost 2 years of gathering evidence/statements etc. from family and friends before the police could formally charge the accused.
The crown also put a publication ban on the case, they do by default in most of these kinds of cases to protect the identity of the victims (can be removed if the victim appeals, and they want the info to be public)
Very likely that, that is the same case here. Lots of women and girls don't come forward for several years because of being threatened and fear of their image being tainted in public. Sure there are instances of "false claims" but over 90% of the time that is not the case. It is a LOT of work/stress for all the family members involved, people don't just pull that for no reason.
If they've been told to surrender themselves, they have to within a set time frame, otherwise there will be a nation wide warrant out for their arrest and then their names will be public. Also they don't tell people to just surrender themselves unless they have sufficient evidence that suggests that the accused is guilty.