I note from the website there is free 'customer' parking at Brent Cross Shopping Centre. I presume that is officially only while you are on site? What is not clear (perhaps unsurprisingly) is how far you can push it. There is just no time limit specified at all. It's a long shot, but has anyone left their car there and got the bus into town and got away with it? I'm guessing the fact it doesn't open til ten and isn't that close to the tube deters commuters anyway? Before anyone suggest it-from where I live to London it's now £105 day return on the train plus £10 parking at the station. And the National Express takes about 4 hours compared with just over 2 in the car.