11.   The mystery hero immediately alerted police after spotting a bomb.

12.   The police were alerted to the plot by a paid informant.

13.   Police were first alerted when Mr Macdonald called Oxford Police Station with his threat.

14.   Strategically placed video cameras can alert the police to any trouble.

15.   The suspects were followed onto the motorway and shortly after, Wiltshire police were alerted.

16.   The police were alerted, marksmen were drafted in and the area sealed off.

17.   Police were alerted at Teignmouth in Devon after three men allegedly drove away from this petrol station without paying.

18.   Last summer she alerted police after Stephen Davison went missing.

19.   Dyfed Powys police have been alerted.