Arthur, where do you live?
The emission zone is moot. Unless you drive a 7yr old diesel truck which most regular visitors to the zone do not.
Harrods, John Lewis, Bentalls, and Hamleys are not what I would call the major engines of the central london economy, I would imagine the hotel and tourism industry trump them, as do the banking and financial service companies in the city and the hedge funds and private equity in the west end. Retail I would imagine Debenhams Group and whatever the TopShop / Top Man etc group and Next would be a bigger impact and able to cause a bigger stink.
You complained about the stinky buses and taxis not long ago in the emissions thread but failed to note that both pass the emissions standards he is laying down.
There is a thought that if you can spend 80 big ones on a car then another few quid a day to drive it, and well if you live inside the zone with a 90% discount makes the charge less than the cost of a latte it is no big deal.