The crime is perverting the cause of justice. You do not have to conspire.
According to lawyer friends, you would have to show that her actions prevented the proper administration of justice, and that is a hard thing to do. This is why the Gareth Jenkins / Susan Crichton / Simon Clark part of story is so important. I think it is the strongest link between her actions and the disruption of justice (Seema Misra). This is why her and all the lawyers deny knowledge of the Clark advice. Had they properly read and acted upon that advice then the Misra would probably not have been convicted.
You can also be an accessory to a crime, even after the crime has been committed. To my (non legal) brain, she seems to have been an accessory to Jenkins' alleged perjury. I think angela van den Bogard may well be done for perjury. The judge practically accused her of in court, and Beer accused her on making an incorrect statement to the court.
There is also "using a false instrument". This is one of the things Jeffery Archer got done for. He got a friend to write a statement giving him an alibi. On the basis of that statement a case was settled out of court. As it was an out of court settlement, the statement was never presented to a court. He therefore had not committed perjury, but did "use a false instrument to obtain a financial gain". He did commit perjury as well, but the "false instrument" charge was a surprise for him.
Sub postmaster confessions of false accounting were obtained under threat of prosecution for theft. If that threat of a theft charge had no legal basis (because the PO didn't know where the money was and therefore had insufficient evidence to support a theft charge), then maybe the confession was a false instrument that was used to pervert the cause of justice.
I must speak to Lawyer friends.....