Is it illegal to park on the pavement?

[samuel23]

I'm posting this in LAW as well, coz I'm not sure which section to put it in.
Our local paper says that it's only illegal to park on the pavement if the vehicle is 'causing an obstruction, or forcing pedestrians to walk in the road' ~ Now, I thought to myself, surely any vehicle parked on the pavement is causing an obstruction, yet I was going along the A20 into London yesterday (around the Eltham area) there were actually signs / lines etc for vehicles to park half on the path and half on the road. Does anyone know what the legalities of this are? Is it down to individual councils, is it governed by the highway code or are there by-laws that allow it?
Thanks in advance

[Grunty]

I wouldn't normally reply to a question that has been duplicated, but in this case have answered the other one.

[samuel23]

Thanks Grunty ~ I wasnt sure which section would be appropriate, and you know what people are like here ~ very short tempered if they catch something in the wrong section :-(