Retail guru Mary Portas, the undisputed Queen of the British aisles, moves to Channel 4 this month to present a brand new series, Mary Portas: Secret Shopper.

Here, she explains what she's hoping to achieve with her new series, why customers are being sold short in Britain today, and what we can do about it.

What's the series all about?

It's me actually going on the side of the consumer. In the past, my shows have involved me going in to save failing retail businesses. This time I'm looking at it from the customers' point of view.

I just think we've lost the whole culture of service in this country. I think we've ended up with sales teams stacking shop floors as opposed to any type of service. I think it's criminal. We're probably one of the worst countries in the world for customer service now. You don't realise how bad it is until you travel.

There's now a whole generation - certainly my kids, who are teenagers - who don't even expect good service. They don't even expect to be greeted now when they go into a shop.

So I'm looking at that, and how we can improve that. And in some circumstances it's very funny - it's so bad it's funny.

What sort of areas will you be going into?

First of all, fast fashion, where there's just no service anymore. I go into shops like that undercover.

Then I'm also looking at places where you're sold at - the hard sell - so places such as furniture showrooms. I've seen people being sold stuff that they don't need. So we're looking at all types of customer service.

Now, when you go to the supermarket, it's just beep beep, 'Have you got a clubcard?', and that's it. They don't even tell you the price - you have to look at the machine.

It's as if we've lost the ability to communicate or care. I hate it. It's something that I've got so upset about. And as consumers we just accept it. So I'm going to go into businesses and ask them 'Are you genuinely putting the customer first?'. You look at the cultures of these businesses, and you realise nobody on the shop floor is being properly trained or given time, and they're the ones who are the interface with the customer.

Is it much better abroad, then?

Certainly in America it's superb. But they are on commission, so there is the question 'Are they really selling me the right thing?'

But, I went into Bed, Bath and Beyond in America just to buy a cafetiere about three weeks ago, and the guy was just talking me through every type of cafetiere possible. And I said, 'Well actually I only want it because my friend hasn't got a cafetiere and I'm staying here for a week.' And he said 'Well then, it's the cheap version that you want.' He just gave me really brilliant service. I just can't remember having that in the UK.

I'd love to put that into our retail. We're meant to be a nation of shopkeepers, it's the number one social pastime, yet it's hell. Genuinely, it's not fun.

Have you met any resistance from the retailers?

Yeah, but that's what makes good TV! They go, 'No, we look after the customer.' And so you show them the undercover footage.

And then they blame the sales team, and they go 'I trained them!', and then you discover the training is a notice on the back of the door that says 'smile before you go on stage'.

That's your training? And they're paying the minimum wage, and they'll get someone who doesn't speak more than five words of English.

How did you decide who to shine the spotlight on?

We wrote down a list of the ones that we disliked. Then we did a poll of lots and lots of customers, and asked what their hates were. And then we began to realise it was everything.

It wasn't just phone shops or electrical goods. People would go into jewellers and the staff wouldn't know about the product they were selling. It just seemed like such a big issue: we could go anywhere and look at any business and in 90% of cases they wouldn't be putting the customer at the centre of what they do.

Is it all retail that you're dealing with?

Yes it is, because it's very difficult, visually, to show me dealing with phone companies in India. And I felt most strongly about it in the retail sector, because that's where my background is.

I know there are these call centres which are just heinous. But in the last 15 years, it's been a period of very high consumer spend, where anybody could have made money. You didn't have to be good. So this is coming at a time when the consumer has all the cards in their hand.

Often when you get economy dips, which we've got, something good comes out of it. I think we're now becoming a little bit more considered and caring about how we shop.

Were there any places you visited where you were impressed by the standard of service?

Yes. There was an incredibly sophisticated sales operation in this furniture showroom. They had it down to a fine art.

But, even then, was it actually giving what was right for the customer? The more time I spent watching them the more I realised it was all about getting the sale. So, very sophisticated, but not about the customer.

Which companies in general do you think have got it right?

There's hope, when you look at companies such as Apple. They weren't retailers, and came on to the high street and delivered one of the best retail experiences there is today.

They put things such as the Genius Bar in, they gave free advice to people, they trained people, all the guys were geeks who knew their products, and it's successful. And every one that they've opened has been managed that way.

And I think Pret a Manger is one of the best out there. The energy when you go in there is great. Gap do it really well - the sales team have an upbeat freshness and energy about them.

And John Lewis staff are extraordinarily good. They know their stuff, they're pleasant and they'll go out of their way for you.

Do you think even when we're getting cheap prices we should still expect good customer service?

Of course, why wouldn't you? The profit margins are much greater than on luxury goods. You should absolutely expect decent customer service wherever you're shopping.

How do you persuade shopkeepers to invest in their staff and in good customer service? What's in it for them?

I genuinely believe that consumers will see that you've put that extra effort in, and will come back.

I also think that we're culturally shifting towards that - we're questioning where we spend. We've got a much more considered consumer, and, because of the financial crisis, they're looking at what true value is today.

I'm speaking to retailers and saying to them, 'Let's start to be part of this new shift.' And some of the big, global brands are starting to do that.

So how do you go about ensuring that customer service improves?

I think it's a cultural change from two sides. I think it's about the top of the business genuinely, genuinely thinking about their consumer. And I think it's a cultural change from the shopper going, 'Do I really need this? Have I really been looked after? Has this been honest and trustworthy?'

I was filming in a fast fashion shop, and the state of the place was unbelievable. There were clothes on the floor, there were queues of 40 or more people - it was gobsmacking. I wouldn't do that. I think standards have got steadily worse and worse.

Why is that?

If you look at the history of retailing, in the 50s it was all independent retailers. You went to your butcher, your baker, your local fashion shop, and you had small businesses that really needed to serve.

By the 70s, chains started emerging, and the minute you get into chains, trying to keep that service culture is very difficult. You had to grow, and open up other shops across the country, which meant you had to use very cheap labour.

Also, in other countries, there's a certain amount of pride in the job - you go in and you work hard and climb the ladder in retail. Here, a shop assistant just sees themselves as a shop assistant.

What sort of changes did you implement in the course of the series?

Well, to give you one example, I changed the whole fitting-room experience. Shoppers want to be acknowledged, smiled at, they want to be served quickly and efficiently, but the biggest complaint shoppers have is the fitting rooms. The queues, the rooms, the smell. And the staff are bored. They just stand there saying 'only four garments... only four garments.'

I worked in a fitting room for a day during the filming, and I almost lost the will to live. The customers hate it, the staff hate it, how can it be all right? So I looked at creating a new type of fitting room. What would inspire and motivate both the staff and the consumer?

Have you always been a complainer?

Yes, I suppose I have. Ever since I trained at Harrods. Wealthy people have no problem complaining if something isn't up to scratch, and I learned from them.

I think, sometimes, less well-off people don't think they have the right to complain, or they don't have the self-confidence to do so, so they just end up accepting mediocrity or poor service.

You've been tackling problems in retail for years now on telly. Do you ever despair about the task - that things will never improve?

I look at the restaurant industry, which has been on our TVs for 15 years now. I've only been at this four years. I look at what's happened in the restaurant industry and I think there's been a huge shift, from the Bernie Inns to actually understanding what good food is about.

That's all changed through awareness. It'll probably be a few more years yet. But when it's done brilliantly, retail is one of the most exciting, fun things to do. A day at the shops can be wonderful when it's done right.

So I refuse to let the fat cats out there make serious amounts of money and not hear the voice of the consumer.

You've moved from the BBC to Channel 4. What was behind the move?

I loved the BBC, absolutely, but at Channel 4 I felt that commercially I was able to flex myself a bit more, and make a bigger change in a louder way. They're a little bit more racy. It just feels like the right sort of environment to me.