Hi Simon, I noticed that on your blog Matt B said his visa expiry was based on his police check. His medical was in March but his visa expired at the end of July.I have never said the police cert needs to be of any particular age at entry. The rules are applied as of the time of interview - and the CO has some latitude about the age of the police certs. As mentioned above they are considered valid up to 12 months, and will be accepted older than that in the case of a previously visited country.
I have never known a case where the visa validity was shortened because of police cert validity. It is always based on the medical report (medical plus 6 months), and the only time I have known it to be less than 6 months is for certain health conditions. There was a suggestion in one of the lawsuits that Russian cases were commonly being given 3 month validity, but I myself have not seen cases like that - and I think it was a misunderstanding.
I have also never known a case where there was a problem at entry because of a police cert being out of date - and certainly that would have been the case in many of the Gomez case issuances that are being allowed to enter with expired visas, and now very old police certs.
I renewed my police check based on that experience story and, for $42, was worth every cent for the peace of mind.