Annabel Freyberg checks out a book devoted to decorating data
Decoration and detective work aren't the most obvious bedfellows, but, for Nicolette Le Pelley and Cheryl Knorr, tracking down the right person to restore the skylight of a Nash house, dye a fitted carpet in situ, or even paint a Tiepolo on your ceiling, are just the kind of ticklish tasks they relish: the more ticklish the better.

Up until now, that is. After several years as the driving forces of Design Line, a free phone service answering interior design problems, Nicolette and Cheryl realised that they had a pretty good idea of what people wanted - as well as a sensational database of specialist suppliers and craftspeople. They therefore set about compiling the first-ever book devoted to the whereabouts of decorating data. This month their sleuthing sees the light in a publication in conjunction with House & Garden called (unsurprisingly) The House and Garden Book of Essential Addresses.

I hunted them down at Design Line's west London lair: an airy, white weatherboarded, glass-roofed slice of an office wedged between a garden wall and the perfectly slate-floored, National Trust-paint-licked kitchen in Nicolette's home. Ordered, if steep, piles of papers and stacks of home-interest magazines abound. Appropriately, both Design Liners are chic, neat and animated on the subject of accessories , whether these be stair-rope or paint finishes.

When Nicolette set up Design Line some two-and-a-half years ago she had already accumulated eight-and-a-half years' smart decorating experience at World of Interiors magazine - she was deputy editor - which she left to have her first child. Cheryl joined her a few months later, after working as a restaurateur and interior designer.

To their surprise, half of their calls came from the trade. It was from professional decorators that their more unusual requests came: aquariums, gym equipment, the contents of an "English-style" pub (to be assembled in Germany), large clocks showing different time zones across the world. He was put touch with the clockmakers who look after Big Ben.

What, then, have the rest of us been after? Everything, apparently, "from an eiderdown-maker to reclaimed wooden flooring", modern lighting, animal-print wallpaper, ceiling fans and children's furniture. A desperate butler needed replacement blue-glass linings for his salt cellars, and a man in Vienna wanted a London cleaner for his 20 velvet and brocade curtains.

The contents of the book reflect these demands. The fabric and wallpaper sections, for example, are divided into types: "Real and Fake Leather and Suede", "Velvet, Corduroy, Chenille", "Utility Materials, Tickings and Felt" and other classifications. There are good "Restorers", "Gardens" and "Specialist" sections. Suppliers with strong lines in several products are listed under each one.

Imagine, I said, a large crumbling barn. I want to put in panelling and stained glass, paint it gold, fill it with Perspex furniture, piles of fake books and busts of Roman emperors and light it for a party. What would they suggest. "Look in the book," they said. "It's all there." And it was.

`The House & Garden Book of Essential Addresses' (Design Line, pounds 14.99), is available by post from Art Books International Ltd (0171-720 1503)