The housekeeper had called the phones the " musical phones " as one never knew where the phones were going to be plugged in from one day to another,and it would appear that the Chief Supt lied about having used it on the morning of the 7th. At the 2002 appeal,he'd denied having rang the Chief Constable that morning,,but evidence found in 2004 proved that the Chief Supt.Harris,,had indeed used the phone to call Simpson.
This phone, presumably,would have had blood on it,,unless the idiot wiped it before he made the call.
It was the morning of the search of the farmhouse.