How come you think Pc West made mistakes, but Jeremy told lies? Why can't Jeremy have simply made some mistakes when he was incorrect?
Jeremy can't have accidentally told police that he taught sSHeila to fire the murder wepaon and that she fired all wepaons in th ehouse, he clearly lied intentionally.
Jeremy can't have accidentally told police he got the gun out to shoot rabbits and left it and the bullets out when in fact she staged the bullets afterwards and made thw whole story up.
Jeremy can't have made a mistake in claiming Nevill called him, he knew it didn't happen.
Jeremy didn't make a mistake claiming he called police immediately after being unable to get through to Nevill he knew he never tried to reach Nevill and that he called Julie before calling police an dran out the door as soon as he was done with the police. He claimed he called police first because he knew how bad it would look to have called Julie first and figured police would never figure out the truth..
I cna continue but it is all the same, he said things he knew were untrue and said them on purpose to conceal the truth. There are no possible ways for him to have just erred by accident on these matters.