He knew the number.
He had the phone in his hand.
He didn't know the numbers of any individual police station.
He knew a 999 call is answered straight away.
He knew a 999 call is manned 24/7 and always answered.
He knew a 999 call would deal with his query correctly.
He didn't know which individual police stations would be open.
He did not know which individual police stations would answer straight away.
He decided the situation was serious enough to contact the police. So dialling 999 is the obvious thing to do.
Bamber himself said ringing an individual police station 'would make no difference' to how quickly the police arrived. So there is only a big disadvantage, in having to waste time looking up numbers in the Yellow pages.
A 999 call would direct the call to the correct station straight away.
He had two options to dial 999, after there was no answer from Witham police station.
Dialling 999 would be an instant reaction after getting Neville's call.
He wanted things resolved quickly as he tried to call back Neville after the phone went dead. Being unsuccessful doing this, and with the phone in his hand, he will then do the next best thing. Which was to dial 999.
He did not know if an individual police station would have the correct staff available to assist him.
He was half asleep, so would not be analysing things too much. The action which required the least effort was ringing the 999.
He wouldn't know if the Yellow pages would have correct numbers.
Everyone is taught from a young age to dial 999. In an emergency.
No one is taught from a young age to look for police stations numbers in an emergency.
Bamber said he spoke to Julie after the police. So cannot claim Julie advised him to phone a police station directly.
Neville had rang him for assistance now. If Bamber was not going to go there straight away, he would want to meet the police quickly.
A combination of the above.