Why is David Cameron wasting the Met Polices time?

...having them reopen the madie McCain case. Im sure the top brass at the Met will be well pleased, an apparently independent public boby being ordered by the PM to do as he says. During this economically tight time should we be wasting taxpayers money and Police resources on this case, after all the McCains did leave this child alone whilst they went out and drank, should the MET be investigating claims of child abandonment, not alleged child abductuction.