A former sergeant told the Hillsborough inquests he clearly heard a radio message calling for someone to close the gates to the central tunnel on Leppings Lane, which led fans to the two pens that become fatally overcrowded.

Derek Miller, who in 1989 had significant experience policing football matches at Hillsborough, said the message came shortly after he heard an instruction to open gate C, allowing fans outside the ground to enter “en masse”.

Giving evidence to Christina Lambert, counsel to the inquests, the jury heard that Mr Millar arrived at the Leppings Lane entrance at about 2.45pm.

Asked what his impression of the crowd was, Mr Millar said: "I was absolutely shocked when I pulled into Leppings Lane. It was horrendous, the number of fans that were still there trying to get into the ground at that time."

Mr Millar said he saw Superintendent Roger Marshall on a bridge parapet, on the opposite side of the bridge. On his radio, he heard Mr Marshall make a request for one of the gates to be opened and he said if it wasn't done someone was going to die.

Mr Millar said he heard the request two or three times and then Mr Marshal disappeared into the crowd.

Mr Miller told Ms Lambert he went to stand on the parapet where Mr Marshall had been and couldn't see any police officers. Not long after that, he said, the order was given to open the gate and fans rushed in.

He then heard an order to “Open gate C". Asked how confident he was that he heard gate C mentioned in the message, Mr Millar told Ms Lambert he has always had it in his mind.

Mr Miller said he saw the gate opened almost straight after the order and fans went through the gate "en masse".

Before the gate was opened, Mr Millar said the crowd was trying to get into the ground and he saw fans in the body of the crowd getting crushed: "We'd got some climbing up over the top of the turnstiles and obviously dropping down onto the other side. Fans just generally trying to get into the ground."

Asked if he saw fans pushing, he said: "It was a general heave. If you've got 3,000 to 4,000 fans, which there must have been, all pushing towards the turnstiles, that's what you've got."

Mr Millar said standing on top of the parapet he could see the tunnel to the central pens and the small area of the inner concourse.

He said when he was looking he saw just a trickle of fans through turnstiles but did not see any police officers and said he thought that was surprising: "I would have expected to see officers on the central pen tunnel, and probably officers on the entrance to the presto stands [the Leppings Lane stands], which is either side of the centre tunnel."

Mr Millar told Ms Lambert it was then that he heard a radio message asking for somebody to close the central tunnel gates.

"It was a radio message, I don't know whether it came from match control or whether it came from an officer pitch side or whether it came from an officer in the centre pen, I don't know.

"It was to close the centre pen tunnel gates, to stop anybody else, I presume, going down the centre tunnel."

He said the message came a minute or two after he heard the instruction to open gate C, and said the messages were clear on the radio.

Asked why the message about closing the gates to the tunnel was not included in his initial statement, Mr Millar said he didn't know at that time whether there was a serial on the centre pen.

Ms Lambert asked Mr Miller if he thought there were any alternatives to opening the exit gates.

Mr Miller said: "Yes, There's always alternatives. Get some manpower into Leppings Lane to sort the crowd out, or, indeed, postpone the kickoff of the match."

Entrance from tunnel leading to central pens of the Leppings Lane end at Hillsborough - handout photo issued by the Hillsborough Inquests

Earlier, Mr Millar told Ms Lambert he had policed the rear enclosure of the inner concourse as a PC, at previous football matches.

"Once the centre pen was full, we would stop anybody else going into the centre pen, and then filter traffic left and right to the other pens,” he said.

Mr Millar said he remembered the tunnel being closed two or three times, at previous games and on one occasion he closed the gates himself.

Asked who would make the decision that the centre Leppings Lane pens were full, Mr Millar said: "You would hope it would be match control, who had a view of the centre pens, would tell the serial sergeant the centre pen is full, but obviously if you've got an experienced sergeant, he would make the decision."

He said if the sergeant made the decision the control box would be informed.

Mr Millar said the gates would not be locked or bolted, but would be pushed to and officers would stand in front of them.

He said they would be able to estimate how many fans had gone into the centre pen, and if other areas were empty supporters would be directed to those areas instead.

(Proceedings continue)