Have you ever gone shopping for a pint of milk and ended up with a trolley load of other stuff?

Do you know your bog-offs from your planograms?

That goes from GAs, team leaders, section managers, up to store manager if need be.

We take a trip to the front line in the corporate war for your hard earned cash.

Today's battleground is about loyalty and that loyalty is driven by what's important to us as shoppers.

And we'll be hitting the aisles with Britain's canniest shopper, who'll show us how to avoid some of the tricks used to manipulate customers.

I remember the line out of the Lord's Prayer as I go through the supermarket doors and that line is, Lord, lead me not into temptation.

Keep watching and learn how to shop smart.

This is what, for me, I'm just so passionate about it as my team are.

This is at the absolute cutting edge of retail.

Sukhwinder Basi is the general manager of a typical British supermarket.

He's also a commander on the front line of 1 of the biggest commercial battles of the century.

The fight among the supermarket giants for the contents of your wallet.

We spend more than £134 billion on groceries every year and the major chains like Asda, Sainsbury, Morrisons and Tesco are all engaged in an endless struggle for our hearts and minds.

Nothing in a modern supermarket is left to chance.

Everything in the store is carefully thought through and managed to encourage us to spend more money.

And then to come back next week and spend all over again.

To help find some answers, we've gained access to a state-of-the-art 100,000 square foot hypermarket that Tesco have built here in Beckton, East London, just up the road from the 2012 Olympic site.

Using this mega-store as a case study, we'll find out some of the psychological techniques common to all supermarkets.

The stores would like us all to be happy shoppers and Suquinda is clearly a man on a mission.

I honestly believe that the job we do in stores actually makes a difference to people's lives.

We not only provide the bare essentials, but actually we do so much more than that.

You look at our finest ranges, you look at our cosmetics, you look at electrical.

It's no longer about keeping up with the Joneses.

It's actually about getting ahead of the Joneses.

The things we eat and our lifestyle says something about who we are as people.

This vast cathedral of consumption is open 24 hours a day and it's still expanding.

It sells everything from food to HD televisions.

50,000 of us shop here and spend close on 2000000 pounds every single week.

We'll be following a family of typical shoppers to see how they're affected by all the in-store trickery.

With 4 kids to clothe and feed, their weekly shop costs about £150.

In supermarkets speak, they're called premium loyals, the crème de la crème of shoppers, whom all supermarkets would love to attract.

We go in with 1 trolley and we somehow come out always with 2 trolleys.

All of those, they all add up to number 2 trolley.

But no supermarket ever forced a customer to make a purchase.

Their psychological approach is far more subtle, so we'll need some expert advice.

Karl McIver has years of experience as a consultant working with major brands and helping actually to design supermarkets.

If anyone can teach us some of the tricks of the trade, it's him.

Well, we're gonna have a really good look around this store today.

I think the important thing for people to realize is that a big modern supermarket is just not a shop.

And they're always trying to deliver what we call in the trade, retail theatre.

So we're going to follow the runners around the store, have a look what they're buying and then really see what's going on.

Well it's really important for stores to try and drive sales and they'll do that with lots of promotions.

So they like to position those in the promotional aisle and that's exactly where we're going to start.

It's 1 of the most important parts of the overall store layout.

Just like on a map, it's the major motorway throughout the centre of the store.

And once a customer is here, they can usually find their way to everything they're looking for, whether it's big brand promotional deals or any of the individual separate sub-departments.

The power aisle is really the heart of the store and the customer drives all of their decisions from this point.

The supermarkets are well aware of the impact a well-designed power aisle can have.

This is where we put our strongest offers and customer looks down this and says well actually if I can't get it here I can't get it anywhere.

Once in the Power Isle this is where customers can find all the really big deals.

And it's typically where suppliers are keen to get their products in the most important part of the store.

Because of course for every 1 product that a customer will buy, you're going to get another 1 free.

In the industry this is known as a bog off and it's not a rude word.

And those on the inside know just how effective this is.

They even have a nickname for the technique used to manipulate as shoppers.

Different people call it different things.

So we throw the customer a bait, which is we put our strong offers on the end of the aisle.

So as an example, we've got a strong offer on buy 1 get 1 free ski yoghurt which is next to the yoghurt sale so customer would look at that and say wow that's an awesome offer and then entice the customer to look at the rest of the yoghurts.

Carol is analyzing the Ranas every move and will give them feedback once their shopping's done.

The children grab their favourite yoghurts, but they don't read the sign and miss out on the offer.

Realising their mistake, Khaled steps in to make the most of the special deal.

How often do you think you are influenced by the special offers in store?

Quite a lot of times, yeah, because I've got a big family so buy 1, get 1 free.

Okay, so those things are really quite important

Okay, so with that sign, did you notice if there was any particular colour that was being used?

And actually if you notice around the store everything that's got a special price or great value, something that the company really would like you to see, they use yellow as a beacon color to really really stands out and catches your attention.

So you know whether it's a reduced product or a special offer, yellow is used to really draw your eyesight.

And if the special offers work well, they'll entice you to buy more than you actually need.

So working their magic and driving up sales.

Here come the Ranas and Khaled's finding the bog offs irresistible.

So when you were in the health and beauty aisle you bought some shower gel and some shampoo and stuff like that.

Now some of those products were on special offer.

Did you notice that when you were buying them or did you just go for brands that you normally use?

I went for the branded ones first and then while I was there I saw it was buy 1 get 1 free so I picked up 4 in the end.

Oh right okay so you bought more as a result of that special offer?

I bought more as opposed to the offer, yeah.

Okay, now the offer itself was marked differently on the shelf, it had got you know sort of some signage and it was on a different level.

Absolutely and that's exactly where they'd like to position those special offers so you're guaranteed to see it.

Because of course if they're on the lower shelves or they're out of reach, chances are they won't sell quite so many.

So you really did fall for that 1 as well.

So not just buying 2, you actually took 4 home.

Bingo, as far as the supermarkets are concerned.

In order for this whole system to work properly, the staff have to perform.

This store has just undergone a major refit and has a new manager, Sukhwinder.

If I'm honest with you guys I've found a lot of my time going around you know becoming the detail list manager.

Yeah so you know we walk the shop and we say that's not very clean, where's that product, where's that size or what's happening with that shelf edge label.

If we continue down that road 2 things will happen.

1 is I'll keel over and die because I can't keep doing that forever.

And secondly is the bit where, you know, I must wind you guys up as well.

OK, so for me to stop doing that, you guys need to start doing it.

Pep talk over, he takes his management team on a whistle-stop tour of the store to show them what's new.

On this evidence, it's difficult to see what Tesco doesn't sell.

When you went round, did you see stuff that you hadn't seen before?

So actually, if as a management team, you know, we've gone round, we've noticed different things, you know, there's a huge opportunity for us to get our staff to see this, because actually, you know, there's 500 odd ambassadors for the store that can go and talk about all the great things that we're doing at the moment.

And it's not long before the team's hard work begins to pay off.

Just minutes into their shop, the Ranas once again find themselves buying more than they'd planned.

Did you start off today wanting to buy a poster?

sort of wander there somehow while I was, I don't know what I was doing, picking something else up.

Now the stores actually use this as a process called see it, like it and buy it and they're relying on the fact that first of all they want you to fall in love with it and as soon as you like it you have to then be able to put it in your trolley without even thinking about it next.

Impulse buying is the classic way of spending more than you planned.

But amazingly, 8 out of 10 of us no longer use a list when we go shopping, leaving us very vulnerable to temptation.

And there are tens of thousands of desirable items out there.

But we can show you how to avoid these pitfalls.

Prepare to meet the man who may well be Britain's canniest shopper.

This is Stephen Craft, retired scientist and bargain hunter extraordinaire.

He claims to have the supermarkets sussed.

None of their psychological tricks or mind games works on him.

It's like something out of a horror movie.

He's been fitted with a high-tech, infrared, eye-tracking camera.

It will record in pinpoint detail everything he looks at while shopping.

It will allow a team of experts to analyze his conscious and subconscious decision-making.

So can he really resist the temptations that lie in store?

According to the experts behind the eye camera, convenience is king in our hectic, time-poor modern lives.

Today's battleground is about loyalty, and that loyalty is driven by what's important to us as shoppers.

If I can get you in and out of here more efficiently, more quickly, then that's going to start to build towards my loyalty.

Surprisingly, they say that nowadays, price and value for money come way down the list for most of us.

It's clear from the moment he entered the store that he is not behaving like your average shopper.

As you walked into the store you turned left and then walked down the bottom of the store in front of the checkouts.

Is that the route you'd normally take as you come into the store?

Yeah, the reason for that is that I'm heading straight for the bargain shelves where they're selling produce that's coming up to its use-by or its sell-by date.

Stephen knows where the cheapest products and offers are kept, but unlike most of us, he actually compares prices when he sees a special deal.

Well, they have bog-offs and It works out cheaper to buy 2 of certain items.

I'm just trying to work out the worth of about £3.

See, it's still not cheap enough actually, so I'm not going to bother with that.

Most shoppers will see the red and yellow, which they've learned is that means of promotion.

And most shoppers won't actually read the words.

So they're not actually making the decision that you're making in terms of evaluating the actual value.

Not many of us know where these sorts of bargains are to be found in the store and unlike with their more expensive ranges the supermarkets don't make much effort to point them out to us.

According to Stephen shoppers on a budget are forced to travel all over the shop to pick up cheap basics.

Well, they periodically change the layout of the supermarket, and I wish they wouldn't do that without asking me first, so that you actually have to hunt for the staples, the cheap staples that you buy.

I can see with the layout of this supermarket how they're making you go past the more expensive items in the hope that you're impulse buy them.

And then you have to hunt for the staples and in so doing, buy all the other stuff as well that they make the money on.

But even a canny shopper like Stephen knows just how much temptation's out there So he's equipped himself to cope with the pressure.

The other thing that I noticed that was very interesting was as you're going round, you're using a calculator.

Again, is that something that you'd normally do?

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