We ( Police ) routinely escort transplant organs, and teams of surgeons at high speed, so I have a lot of sympathy with this driver. The fact remains however that no service, be it Police or ambulance have legal carte blanche to break traffic law, and every case is judged on its merits, so without the full facts on this case, ie weather conditions, traffic density, road topography etc. it is easy to criticise and jump to ill informed conclusions. This may have been issued by a computer after an automatic camera detected the speed, so no discretion has been applied yet, and the facts will have to be put forward in court.
Police officers are frequently prosecuted for motoring offences which have occured on duty travelling to emergency calls to aid members of the public, if convicted they then suffer increased premiums on their own insurance, and risk their own licences, so this is by no means a unique case.
Just to cover another misconception there is no absolute requirement to have blues and twos on when exceeding the speed limit, the situation at the time dictates their usage, as they can be counter productive.