There was also a big political side to it as well.
Gordon Brown turning up in Portugal a few days after the disappearance was really unusual, especially as it should of fallen under the remit of the foreign office (which i think was Milliband at that time).
Interestingly, the first FO liaison allocated to the McCanns, warned the Government regarding them, along the lines of 'be careful of hitching your horse to this carriage' as there was a lot of inconsistancies and holes in their version of events.
After Brown got involved she was swiftly moved on, off the McCann case.