Thousands of people drive up and down the A1 every day, stopping off at fast-food outlets and petrol stations. But something else lines one of England's busiest roads: sex shops. Why are they there and, in the age of the internet, who is going in?

Lingerie, handcuffs, synthetic body parts and a £1,500 sex doll - they are all available to buy next to a Shell garage on the northbound carriageway between Doncaster and Pontefract.

There are seven Pulse & Cocktails adult superstores in total, which occupy former roadside restaurants - mostly Little Chefs. On the A1, a major trunk road connecting London and Edinburgh, there are three stores. This caused comedian Alan Carr to pose the question on Twitter: "How horny are the drivers on the A1?"

Quite, as it turns out. But why is Britain's longest road such a handy location for selling sex paraphernalia?

"The [shops] are good for a number of reasons," said Graham Kidd, one of the directors of Pulse & Cocktails, which has been in business for 21 years. "They have good car parking, they are high profile and they are discreet - you're not likely to run into your neighbour inside.

"We can never get away from the fact that we are British and everyone is frightened to death of being seen going into a local adult store, but if they are 100 miles from home they have the confidence to go in."

The shops are fairly isolated in that they are situated away from schools and town centres and communities likely to complain. Inside, the buildings are modern, open plan and well-lit. They are a far cry from the seedy backstreet stores seen as typical of Britain's sex shop offering.

"When we first opened a roadside shop it was a step into the dark, we did not know what to expect," said Mr Kidd. "People objected in the early days because they did not know what it was going to be. It's not like we are next to schools; our shops are very remote and look very tasteful from the outside.

"I do understand why people talk about us, after all we have taken over a number of old Little Chefs, which was an iconic British brand. The risk has paid off though; they are more popular than our city centre shops."

Sex shops used to be aimed squarely at men, while women bought sex toys at "parties" men were not invited to - opening up a gap in the market, said Mr Kidd. "We felt there was a need for somewhere a couple could go and shop together for toys they could use together," he said.

The stereotype that the majority of those visiting roadside sex shops are long-distance truckers is also false, with less than 7% of Pulse & Cocktails' clientele falling into this category.

About 500 people visit the store on the A1 southbound at Grantham every week, estimates manager Michaela Snell. She said most will buy something and roughly 25% of people walking through the doors are regulars. "It's intriguing to a lot of people - they might drive by several times before they eventually come in, but they will come in to see what it is about."

The uninitiated will often turn right into the less intimidating lingerie department, while more seasoned shoppers head straight for the sex toys or bondage area.

"We say hello to everyone that comes in," said Ms Snell. "Some will come straight up and ask questions, others will look as if to say 'oh God, don't talk to me', which is fine - we can gauge what people want and leave them to it. We get a real mix of people in here... we do get a lot of people just asking for directions as well."

According to a recent survey by a condom company, 79% of women and 58% of men who took part said they used sex toys. For those who are reluctant to visit a sex shop in person to make a purchase, there are plenty of places to shop online.

But others find visiting a store helpful when choosing merchandise. One couple buying flavoured condoms in the Grantham store said seeing items before buying was part of the appeal. They said the first time they went in the shop was "very nerve-wracking" but the anonymity offered by a roadside store was what took them to the A1.

Richard Longhurst, co-founder of online retailer Lovehoney, said it is this combination that keeps the bricks and mortar retail offering viable.

"I think there's room for both shops and the internet. You can see quite naturally that it's the perfect product to sell online because of the discretion, because people might be nervous about asking questions about the product. To do that face to face in a shop is quite daunting. But for some people, they like to go and touch and fondle and squeeze, they like to try the clothing on before they buy it.

"So there's definitely a market for both. But we've seen big growth online; for us it's the future of this market."

Mr Kidd said the firm's physical stores get far more traffic than its online shop and its biggest sellers are high-end, rechargeable sex toys. Simply put, "people want to see them before they buy them", he said.

In the 12 years Ms Snell has been at the company - choosing working in a sex shop over a High Street clothes store - she has seen people becoming "more open and understanding" about sex. The Fifty Shades of Grey franchise, in particular, has encouraged people to experiment, she added, with more and more young people coming in "wanting to spice up their sex life".

"I do like working here, I made the right decision," she said. "This appeals to me more, it's a bit more fun and adventurous.

"It's a business though, it's not all fun and games... but it is mostly fun and games."