I agree with Chocolate_Frog, since the police never warn anybody of an impending raid, why start now.
The police have a responsibility to act upon information/intelligence received in a manner commensurate with the level or type of threat. The threat of a biological or chemical weapon being used means fast and hard. No warnings.
Simple answer , keep a list of every one who complains about the recent police action , next time there is a terrorist , or suspected terrorist incident round them up and send them in.
Lets see how good they are at gobbing off then
The Metropolitan Police cordially invite all residents of Betty Boothroyd Street, E.17 to a raid, in particular Mr Hassan Hassan Khan and his brother Mr Hassan Khan at number 6. The raid is to determine if the intelligence obtained corresponds with fact and items such as weapons, chemicals or terrorist paraphernalia are high on our list. To assist would all doors be left open and this way, disruption will be kept to an absolute minimum. Local clerics, the media, and a team of trained counsellors as well as a team of untrained councillors will be available for those that need advice. A police canteen wagon will be parked at the far end of the street and will sell a variety of excellent snacks to suit all persuasions. Dress optional but no pyjamas. Prayer mats at no extra charge.
The raid will commence at 06.00 and while every effort will be made to conclude as soon as possible, the duration of the raid cannot be estimated at this moment in time. We thank in advance for your cooperation and apologize for any inconvenience caused.