This is exactly the Scenario we can expect in the UK
This is EXACTLY the scenario we can expect in the UK if they can hold "suspects" for more than a few days without charging them. They're already up to 30 days and still trying to push for 42.
There are two procedures we can introduce to control this behaviour. First, it is foolish to deny that there are occasions when we will have to detain suspects indefinitely for a variety of reasons, some of which we can't even foresee. However, should that EVER be the case, we must not let politicians, police or judges be empowered to make decisions which restrict the liberty of the citizen without due process. Such powers should only be exercised by We The People in the form of a duly sworn Jury.
Second, when it emerges, as it did in the this case, that no charges are to be laid, the suspect must be compensated for loss and injury and the State must be penalised. Where appropriate, decision makers should be prosecuted or at least fired and the State should pay a substantial fine (£1million plus) in the form of a charitable donation to one of the recognised organisations (Liberty, ACLU etc) who make it their business to defend victims in this situation.
What this would achieve is a strong disincentive for the State to practice licensed terrorism against its own citizens while still permitting unrestricted detention when a Jury has been properly convinced that it genuinely is necessary.