it does seen to be the norm to ignore. The net is full of similar, however i am aware that if you look long and hard enough on the internet you will find something or someone who will tell you exactly what you want to hear. Thing is i have yet to see any basis for this "ledgaly ignoring what would appear to be an ilegal demand for money"approach.
Is the demand illegal? As they(forums mostly) say it is? Cant see it as being illegal as such who would have the forsight to right a law for that.
Spoke to my ledgal advice line and they advise the usual hard line approach. You enter into a contract by parking there. Chocolate tea pot she was. Not interested in the fact you have to park to see the sign in the first place and reading is impossible while your moving along in the car, bloody dangerous in fact.
I think the point is that, despite the fact that they word their demands as "fixed penalty notices", etc. Demands from private parking companies are a world apart from demands resulting from traffic offences on the public highway.
You enter into a civil contract when you park there, true. However, it requires them to take you to court to enforce that contract and the terms have to be reasonable.
If you can show, for example, that your bad parking didn't cost them 90 quid you would stand a good chance of winning. You could probably also argue that the terms of the contract were not clear at the time you entered into it (there'll be some small print hidden on a lamp post somewhere in the car park but can you reasonably be expected to have noticed it?).
In most cases, they know that the odds are stacked against them should they choose to take it to court - so they won't.
Kevin