When they built the original Westfield in Shepherd's Bush, you could see the point as its status as the first inner London mega-mall made it an instant draw.
By the time they brought us Westfield Stratford City, something extra was needed and this was provided by the Olympics: go to the Olympic stadium and you'll have to wander through Stratford's Westfield on the way to watching British athletes come fourth.
That puts a lot of pressure on Croydon, the site of the next Westfield. What will be its x factor?
One possible angle could be to play on the southern suburb's wide variety of cultural backgrounds, so the old Whitgift centre would become a kind of 'welcome to the world' mall. Or, as a charming commenter in the Telegraph puts it:
"What the authorities in Croydon don't tell you is that it's an ethnic cesspit. The place is teaming with low-enders, both local and foreign. Invest there at your peril."
Probably the idea is that there are plenty of people with money in Surrey to make up for the "teeming low-enders", but it will be interesting to see how the two groups rub along together in the wake of the Croydon riots and in the middle of a never-ending economic slump. Could the whole Westfield idea go south when it goes south?