Its often been said that Jeremy being unable to call Nevil back is because Nevil had began making a call to the police. However if Nevill left the phone off the hook, Jeremy would need to keep his phone on the hook for two minutes in order to be disengaged and call out again.
"I understand that a question had been asked as follows: If caller A from Tollesbury had phoned caller B at Goldhanger and during the course of the call, caller A had placed the receiver down, but not on the hook. Would caller B he able to dial out again. The basic answer to this question is yes caller B could call out again on his line provided caller. B had replaced his, receiver on the hook for a continuous period of 1-2 minutes. There is no exact period of time up to 2 minutes.
I must stress that the period must be continuous. If caller B picked up the receiver say for a moment before the 'force-release' period had ended then the 'force release' period would begin again. The 'force release' period is up to 2 minutes although I cannot state what the minimum period is. "
Maybe Bews was right. Maybe Jeremy did call Whitman police station. He didn't get through because his own line was still engaged. And once he found the number for Chelmsford those two minutes were up. And hence got through.