It looks like an ordinary throw, except the design is printed as outlines that you colour in yourself. Most measure around 150 x 125 cm and come with a set of pens in the box.

There is no set order: one flower tonight, a corner of the pattern tomorrow. Several people can colour at once, so it suits couples, friends or a quiet evening round the table.

Many designs are printed as white outlines on a black background, which gives a stained-glass look once coloured. Large areas fill quickly; small detailed zones take longer but look striking when finished.

What makes the difference is the washable ink. With water-based washable pens, manufacturers state that the colour comes out in a normal machine wash, so the same design can be coloured again. The care label sets the temperature and drying.

Some people switch to permanent pens for a finished blanket they want to keep as it is. Just keep track of which areas were done in which ink.

A few practical tips help. Pull the fabric flat on the table and cap each pen as soon as you put it down. Testing a colour on a small corner shows how it looks on the fabric.

It is an easy way to keep your hands busy while chatting or listening to music. And once coloured, it is still a cosy throw for the sofa.

the colouring-blanket.co.uk shop