You know a shopping district is popular when it requires an NYPD officer for crowd control.

Horns from yellow taxis blare on Fifth Avenue as journeys across the city are stalled by hordes of shoppers crossing sidewalks, directed by whistle trills and white glove commands.

Working in fashion, I've always raved that the UK has the best high street in the world. On my most recent visit to New York, I'm forced to eat my words with a side order of salted pretzels...

In the last five years, the shopping scene here has changed dramatically.

Concept stores have sprung up, fusing fashion with rooftop hangouts and even flower shops. Once home to only expensive designer labels, Fifth Avenue is now peppered with high street chains such as H&M and Banana Republic, while, conversely, hip downtown now houses catwalk giants, such as the newly opened Celine store.

Upscale and affordable have merged. For the shopper, that means a more varied retail playground. On my own trip to uptown Fifth Avenue, I barely spot the distinctive upper-crust pearl and twin-set brigade.

In my favourite shopping district of SoHo, macaroon stands decorate street corners and a queue runs out of the door for Georgetown designer cupcakes on Mercer Street. Even the street market stalls have an upmarket feel, selling rose gold jewellery and one-off arty prints.

Hypnotised by a window display of shoes, I wander into Barneys on Wooster Street, one of four Barneys department stores in New York selling high-end style in anurban setting with white walls and concrete floors.

I stroke the Alexander Wang bags as if they were kittens and a shop assistant swoops to my arm candy aid.

"Oh, you're British," he quickly observes. "The Brits just love Alexander Wang and 3.1 Phillip Lim bags... It's a big saving," he says in a hushed tone, before pointing to the store's best-selling Pashli satchel. It's a snip at $895 (£560) - I spied the very same bag for £740 in Selfridges.

Undoubtedly one of the biggest attractions of shopping in New York is hunting down the same US brands for a fraction of the price that you might find them at home, made even more appealing by a favourable exchange rate.

We dash from one shopping district to the next, using the city's neat grid system. The moment I'm in midtown, it's virtually impossible to lose sight of my landmark hotel on the edge of leafy Central Park.

The new Park Hyatt occupies the first 25 floors of the skyline-dominating 90-storey One57 building. Rooms have floor-to-ceiling windows, allowing you to soak up the buzz of midtown from a height. For technophiles, remote controls bring down screens at dusk and switch on a hidden television in the bathroom mirror .

I retreat to the impossibly luxurious Spa Nalai on the 25th floor. I swim in the heated pool piped with underwater music from Carnegie Hall. To bring me back down from a post-shopping high, I experience the spa's signature treatment - a massage on a warm, sand quartz bed.

"Ooh," my massage therapist remarks, kneading my knots. "Your arms and shoulders feel very tight. Have you been carrying a lot of bags?"

My shopping addiction rumbled at the massage table! Now that's a first...