I'd need a considerable deposit or a Legal Aid Certificate first Eric.
Seriously though, pretty much anything can be challenged, often successfully , and what might seem to be very clear language in an Act is rarely as clear as it seems. There are also various strategies which might be employed to " time out" any objection to what the executive has already done.
For example , the ' new' caution warns people that if they fail to mention something when questioned which they later rely upon in their defence , that the Court can make a " proper inference" from that. This is the law , and yet it's generally meaningless because you can almost always overcome it with reference to the Common Law right of a man not to condemn himself - ie to incriminate himself.
If you were to read the relevant legislation though, without the necessary knowledge and experience to know this, ( which is very very easy), you'd think it meant what it says, wouldn't you ? Now, I mention this merely to illustrate that sometimes various other stuff "trumps" an Act of Parliament, and that's a very very wide subject which we cannot adequately cover here.
I repeat that anything can be challenged , and I'm not even certain that the Act you mention is the one which applies here - it's certainly not the only one which could .