Police records are typically based on your full name and date of birth, plus having your addresses will make checking records relatively easy.
Australia asks you to obtain certificates from the police force of any country in which you have lived for more than 6 months in the previous 10 years. I suspect that the SIR ask for your addresses over the past 5 years for the same reason, the implication being that they do not check any further back than this.
CS is quite definite about his opinions, and I'm inclined to think that he is correct. Most countries do keep central criminal records, and there must surely be established protocols for exchanging informations about criminals.
Another question is what types/severity of criminal offences would result in a refusal of an EP or PR? Drug and sex offences are likely to be taken very seriously I'm sure.