There is a lot of dispute about whether the 'mysterious' phone call from Neville was made.
There are at least 19 reasons/facts why Neville would not make the call. Neville would just have to think of one reason/fact to not do so. No one seems sure what Sheila was supposed to be doing when Neville made the call. The most popular explanation being that Sheila had locked herself in the toilet. To be honest, Neville would not phone Jeremy in that situation. Jeremy told the police later that night Sheila was a 'nutter' and 'we don't get on at all, I'don't like her & she doesn't like me'.
Anyway, let's pretend the phone call happened.
Neville was going to leave a message on Jeremys answering machine. Which hopefully Jeremy would hear. However unlike today's 24/7 messaging services, answering machines were apparently switched off & on in the 80's. Although I never met anyone that did this. A shame as a saved message would have cleared Jeremy.
Not to worry, Neville will wait until Jeremy answers the phone. Neville could have a long wait for Jeremy to answer his downstairs phone. Jeremy said he was 'sleeping like a log' that night. Hopefully Sheila is not too crazy at this time.
Jeremy eventually answers the phone. 'Please come over, Sheila has gone crazy and she has got the gun'. The phone suddenly goes dead & Jeremy cannot get a connection when ringing back.
Jeremy rushes over. Er no he rings up Mugford (according to Jeremy). Why did he ring her ? asked the police at a later date. 'No comment' said Jeremy. It's all so confusing.
Surely after his late night chat with Mugford he will speed over as Neville liked to keep things private. Er no, Jeremy checks Yello Pages & phones a police station miles away. Jeremy said 'it did not occur to him' to ring 999 ? All the while Sheila is going crazy & got has the gun.
Jeremy asks the police to pick him up, although he could drive there in 5 minutes.
Jeremy eventually drives over, very slowly, arriving after the police.
None of it makes sense.