"So, as a customer what mark out of 10 would you give Westfield?" I ask a group of 12 students of different ethnicities as we stand outside the Costa coffee shop on the ground floor of the shopping mall in Shepherd's Bush having just completed a two-hour walkabout. The lowest mark is eight and the highest is nine and the average is 8.5.
A few weeks previously, the same students had been asked to go out by themselves and evaluate their local high street taking in a wide variety of locations including "town centres" in Hackney, Wimbledon, Epsom, and Woking. The average mark in terms of customer satisfaction varied between four and six, with an average of 5.2. The difference between experiences in Westfield London and local high streets is considerable, then. Agreed, the students are not a representative sample of the UK population -- they are observing consumer behaviour as part of their undergraduate study and none of them have established independent households so their needs are relatively simple -- but the scores reflect something about the attractiveness of safe, brand-new and very sparkly shopping centres at least for this group of young people.
Mary Portas, who became a household name after starring in the BBC 2 series "Mary Queen of Shops" in 2007, has come in for both praise and criticism for her review of high streets up and down the land. Many of the 28 recommendations that Portas makes including encouraging street markets, changes in business rates, restricting the number of charity and betting shops, and giving local authorities more power to encourage landlords to rent out premises to retailers are very sensible.
Certainly Simon Kelner , writing in the Independent, thinks so. He argues that it is precisely these sorts of policies that he thinks would transform the fortunes of the ailing high street in the Oxfordshire town of Woodstock -- part of the Prime Minister's constituency -- which has lost a butcher, fishmonger, greengrocer, hardware store and sweet shop in recent years.
An editorial in the Financial Times, however, is pessimistic that anything will do the trick and reckons that the coalition government's unpaid retail czar's "mixed bag of proposals" will do little to reverse the decline in many areas as the Internet and out-of-town shopping continues to grow. The answer, according to the FT is to manage the decline of the UK high street "carefully".
But this flies in the face of the evidence in at least some parts of the capital. Take Commercial Street in east London, for example. Not that many years ago, the road running between Aldgate and Shoreditch was derelict apart from a few clothing wholesalers and retail shops selling clothes and shoes at bargain-basement prices, mainly targeting the poor south Asians who lived in the area.
Now it is being transformed into something quite different. Apart from a few chains like All Saints and Urban Outfitters and a Tesco Express the area, including Spitalfields Market, is awash with cutting-edge retail stores and stalls, bars cafes and restaurants targeting predominantly young, white middle-class consumers. Even an old East End pub like The Ten Bells has been transformed by the addition of high-end, pop-up catering from chefs who have worked at two Michelin-starred restaurants like The Ledbury and Noma.
That's not all. The area is now exporting its successes. The critically acclaimed Hawksmoor steakhouse has recently added two more branches in the capital, one in Seven Dials and the other in the Guildhall area. Return in five years and the street will be completely transformed, and one can only hope that the independently-owned shops will outnumber the chains by a wide margin.
A critic might object that the area is untypical, a beneficiary of the considerable affluence of the nation's capital, which has survived so far the economic headwinds blowing in from the rest of the continent and elsewhere. But head south on Commercial Street and turn left and eventually you'll end up near the tube station in Whitechapel High Street. This is a very different area. Most of the shop and stall owners are of Indian and Bangladeshi heritage. The customers are nearly all Bangladeshi and they are out in significant numbers. These shoppers are not affluent and most live in social housing. But this is their local high street and the stallholders and shops offer something that the nearby Sainsbury's hypermarket doesn't - keenly priced fruit and vegetables some of which originate on the Indian subcontinent, clothing, jewellery, luggage and mobile phones.
The key element in the success of all three locations -- Westfield London, Commercial Street and Whitechapel High Street -- is that they offer consumers from different segments of the population something different from that available in conventional high streets, supermarkets or on the internet.
Mary Portas knows that differentiation is the key and has done her level best to highlight the relevant issues, including pointing out the crucial fact that the complex culture of the high street cannot be reduced to economics. Yesterday, business correspondent Simon English  writing in The Independent dismissed the high street review as an exercise in further promoting the already successful Mary Portas brand. But even if true this confuses the logical status of the recommendations with the motives that may or may not lie behind them. That's far too cynical, even for these post-modern and economically challenging times.
Dr Sean Carey is visiting lecturer in the Business School, University of Roehampton