Cost is always a consideration....no matter where you are in the world.
Ask yourself this question....if the aircraft is replaced....what changes will be made in the security setup that exists now?
What changes will other Police Units do as well?
They will not get rid of the aircraft as they play a valuable role but they will improve the security at some cost. Otherwise the next time a successful attack takes place the management will be looking like monkeys for sure.
What costs resulted from the attack in question? Add in the loss of capability that will exist until the replacement aircraft is obtained....put a Pound Sterling cost to that!
Add in the embarrassment factor....both for the Police and the Airport.
Now add in the costs that are bound to occur when other airports begin to reassess their own security arrangements.
This has been an "expensive" event beyond the non-budget expenditures that were caused to the Police Air Unit.
No matter how one winds up with a foot in a pile of dung....you have to accept the fact you put it there.