While loitering in my local Costcutter, musing on the relative merits of a microwavable sponge pudding versus a can of creamed tapioca, my train of thought was derailed by an unexpected sound. “Costcutter Digital Radio. Making Value Sound Even Better. Around The Country, Around The Corner!” A benevolent DJ then informed me of potential savings on multipacks of crisps, before deftly segueing into a horribly bland track by Australian duo Savage Garden. National instore radio stations such as these have considerable power to inform and possibly irritate their enormous captive audience; we of course have very little power, unable to wrest control of either the volume knob or the off switch. It’s entirely possible that I’ve been gently manipulated into parting with hundreds of pounds in various shops over the years, benignly strong-armed into compliance thanks to calming selections from Fleetwood Mac’s back catalogue. But who decides the soundtrack to our shopping excursions?

The Officers Club is a chain of cut-price men’s clothing stores whose carefully chosen hits from yesteryear are the sirens that lure you from the pavement towards their Phatbastard Jeans and Jokers Fun Soxs. On a quiet Wednesday afternoon in their Oxford Street shoe department, Tiffany is belting out her 1988 hit “I Think We’re Alone Now” over the PA, and as a lonely sales assistant sits picking his nails she carries on, with impressively accurate intuition: “There doesn’t seem to be anyone around.” An announcement cuts in, with the soaring and plummeting syllable stresses of a breakfast show DJ: “WELcome if you’ve just walked in. WE’ve got prices which will AMAze you. Shoes from SEVen pounds FIFty a pair. Why not buy TWO?”

The voice belongs to Debbie Foster, a former broadcaster on Newcastle’s Metro FM. Together with fellow DJ Neil Finan she co-owns Instore Radio Productions, who for the last 3 years have supplied clients as diverse as PC World and Manpower Job Clubs with specially tailored CD compilations of music and voiceovers. Finan: “We were out shopping one day and were struck by how awful the muzak and announcements were in most stores. With our strong radio background, we knew that we could do a lot better.” Their brief from The Officers Club is to assemble a mixture of chart and classic tunes, but playlists come at a price: both the stores and the production companies supplying the music require licenses from the PPL (Phonographic Performance Limited) who collect and distribute royalties when recorded music is played in public. Foster: “It was a shock for us to have to come up with £20,000 before we could duplicate a single CD. For the first 18 months of running the business we couldn’t pay ourselves a penny.”

It’s easy to see why hairdressers are content to eschew a license and keep their customers entertained with Radio 1 or Heart 106.2, as even repeatedly playing a battered Duran Duran LP would mean forking out around £80 a year to the PPL. For companies with a string of stores the sums can become prohibitively expensive, but a study by psychologist Dr Adrian North into the effect of music on consumers concludes that tailoring instore sounds could be worth the extra costs incurred. Slower music, for example, “leads to customers moving about more slowly, browsing more, and consequently spending more.”

I’m sure many of us have never thought to question why we end up with lighter wallets after brief exposure to Enya’s “Orinoco Flow”. Nor have we asked why many of the instore stations try to adopt a sheen of static-free radio credibility by suffixing their names with “FM”, despite “narrowcasting” their shows rather than broadcasting them across the hallowed FM frequencies. Homebase FM is programmed by a company called MBS Datacom, and Adam Williams, their radio co-ordinator, shows me around their West End premises. We enter a tiny room, empty save for a mixing desk, an imposing Homebase logo, a computer scrolling through a list of titles and a CD jukebox, whirring and clattering every 3 minutes or so. We sit there for a while, politely listening to the same feed that is going out via satellite to every Homebase store in the country, and I realise that despite the dedicated studio, Homebase FM is essentially on autopilot. Adam explains. “The jukebox contains 300 CDs, and each individual track is computer-coded according to the type of music, the speed of the song, and the time of day it’s best suited to – for example, tracks that appeal to older customers would be played in the morning, with more modern tunes after work. It probably takes me about half an hour to compile a day’s programming.” The depressingly familiar sound of Darius Danesh fades out, giving way to some advice on changing my walls. “Change your walls with Homebase’s new Living With Colours range… Looks great in any room!” I’m slightly disappointed that I’m not going to meet the voice of Homebase FM, Adriano Russo, who only comes in for a couple of hours every month to record the scripts that are sent through from Homebase’s PR department. “Their priority is always advertising, so even when there aren’t many special offers running we’ll still have to record links like ‘Why not visit our wallpaper section?’”

These links are designed to be easily slotted in at any point in the programme, but their use betrays Homebase FM as being, in instore radio-speak, merely ‘As Live’. Which actually translates as ‘Not Live’. “A great song there…” says Mr Russo, before news of another series of price-slashing deals. “Now, back to the music!” But to their credit, the playlist does seem slightly racier than that of The Officers Club. Williams: “We try and keep up to date, and sometimes we play singles before they’re released – but many record companies see retail radio as a bit of a joke and don’t keep us in the loop. We do have to keep things light, though. I’d love to put the new Radiohead single on our playlist, but that kind of thing just isn’t right for Homebase.” Things do hot up a little after the store shuts, however. Homebase FM continues around the clock, to make the warehouse-like premises marginally less bleak for the people who work overnight replenishing shelves. Adam has more of a free rein during the small hours, but still has to consider the varying tastes of the employees. “If I program too much indie rock, the staff who prefer dance will get pissed off. I’ve got to try and keep everyone happy.” Before the store opens in the morning there is also an anomalous 90 second news bulletin, recorded by a journalist based in South Africa before being sent via an ISDN link to London. Odd.

Topps Tiles introduced Tiles FM into their stores about 4 years ago, and Leeds based company Teamtalk are contracted to provide a live radio show for 8 hours a day, taking staff dedications by email and providing news, weather and celebrity gossip as well as the ubiquitous adverts. Teamtalk’s Mark Woodhead: “To have live DJs is unique amongst stores of this type, and the reason Topps Tiles chose to do it was basically down to staff motivation.” In fact, the station proved so popular with employees that the interactive element of the shows had to be cut back as staff were spending too much time competing at Tiles FM quizzes instead of serving customers. At the Mitcham branch, sales assistant Asvin Shah has nothing but praise for the station. “The music is great, we have sports news every hour, and we can phone up and talk on air if we want… although I’ve never done it, I’d probably say something stupid.” As I browse the glueless laminate flooring section I’m struck by the cheery bonhomie of DJ Nolan Kane, although given his listeners’ limited opportunities for travel, the weather report has a slightly cruel edge: “Here in the UK it’ll be overcast for the rest of the day. In New York it’s 26 degrees with light cloud, Tokyo 24 with cloud, and Athens 28 degrees and sunny… This is N-Trance with “Set You Free”! This goes out to everyone in the Failsworth branch!”

Virgin Megastore Radio is probably the best regarded of all the instores, with DJ alumni now working at stations such as XFM and Kiss. The satellite feed from Oxford Street in London goes out to 93 Virgin record stores around the UK and Ireland, and has accumulated sufficient kudos for bands such as The Charlatans and Spiritualised to pop in for interviews, and for the likes of Grandmaster Flash and Basement Jaxx to do guest DJ spots. New releases are predominant, along with a sprinkling of tracks from older “Essential Albums”. While we tap our feet to “The Boys Are Back In Town”, Nigel Smith the station manager explains Thin Lizzy’s presence on the playlist: “We’ll play a song from each Essential Album every 2 hours, and the record companies will pay us for that exposure.” It’s probably the only radio station where this practice of paying for airplay is upfront and open. But DJ Jon Hillcock points out that despite this small payola element, it’s important that they sound like a real radio station and and avoid the hard sell. “We don’t mention the prices of the releases. And we do actually talk about the music – we’re not here to waffle aimlessly about what’s in this morning’s newspapers.” Samanthi Jayawardena, who looks after VMR’s traffic-free “drivetime” slot, agrees. “I wouldn’t describe myself as a ‘Top Marketing Tool DJ’! I started off doing student radio in Leeds, and see this as a natural progression to proper radio.” Hillcock defends VMR’s credibility with a movie parallel. “There’s a bit in the film High Fidelity when John Cusack [the record store owner] says ‘I am now going to sell five copies of “The 3 EPs” by The Beta Band.’ He plays one of the tracks on the store’s CD player, and before it’s finished he’s shifted the lot. It’s a great moment – and we’re just doing the same thing.” It could be argued that this makes it the most cynically motivated of all the instore stations, but the enthusiasm of the DJs and their genuinely adventurous playlists allows me to forgive them.

A call to Costcutter’s head office informs me that the station that kickstarted my retail radio odyssey is actually available on Sky Digital. So anyone can tune in? “Yes,,, I suppose they could if they really wanted to”, comes the reply. A few minutes of tinkering with my set top box, and bingo! I have immediate access to golden oldies from Wham! and Rick Astley. “Costcutter Digital Radio. Tomorrow’s Hits Today!” trills the jingle, somewhat deludedly. I compose my own catchy alternative – “Yesterday’s Hits, Cheap Chocolate Mousse!” – before exercising the ultimate consumer power: turning the station OFF.