Well yes, of course it would have been significant then. As I said, I have that same phone, and I don't think there's a redial option on it. It's just the old-fashioned type with an old-fashioned dial.
I have found it in Lomax's book. Chapter 14 'The Telephone Call' page 198
'The office telephone was seized and, because it was a relatively modern touch dial telephone, it had a last number dialled facility'
Documentary evidence uncovered prior to 2002 appeal showed
one of the Tactical Firearms Officers, ..... used the telephone to contact the station for some reason. '
'Documentary evidence has since come to light which shows that a request was made at 8.20 for the Assistant Chief Constable of Essex Police, Peter Simpson to speak with Detective Chief Inspector Harris using a land line, which could only be the telephone in White House Farm. '
He goes on to discuss this at greater length.
I know there was much discussion of the office telephone on the forum probably a few years ago. Hope this clears up my posts from last night.