Yes, the advice to ignore the charge is not sound and the parking companies most certainly will take legal action to recover these debts. Take a visit to your local County Court for confirmation of this.
I’ve had a quick glance at the legislation kindly provided by Chris (which I had not seen before) and, apart from discrepancies such as time periods and other technical issues, I cannot see any way you can avoid payment, mrs_o.
I think it was drafted precisely to address the situation you describe where registered keepers of vehicles could avoid payment of parking charges simply by denying the fact that they were driving and failing to say who was. It is similar (though not identical) to the way Section 172 of the Road Traffic Act deals with certain traffic offences, most notably speeding. The difference is that S172 establishes a separate offence of failing to provide the driver’s details which can be prosecuted against the Registered Keeper (RK) regardless of the original offence. The 2012 parking legislation does not do this but simply allows the parking company to pursue the debt from the RK. Another key difference is that S172 provides a statutory defence that the RK can use in that he shall be not guilty if “…he did not know and could not with reasonable diligence have ascertained who the driver of the vehicle was.” The 2012 parking legislation does not seem to provide such a defence.