Some enthusiasts (known as dissectologists) also appreciate the jigsaw as a shrewd investment. Over the past decade the value of vintage puzzles has climbed steadily, with sets once fetching £200 now worth £500. The rarest can sell for thousands of pounds.

It is a far cry from the Seventies when early wooden sets were usually thrown away as junk or sold for pennies at jumble sales.

Therapy: Collector David Cooper says jigsaw puzzles are a great stress-buster and help to keep the mind agile

David Cooper, 60, from Herne Bay, Kent, fell in love with jigsaws as a seven-year-old and began collecting them as an adult. He runs the British Jigsaw Puzzle Library.

'I picked up three puzzles for a couple of bob [10p] at a church jumble sale and was stunned at the quality of one of them,' he says.

'Until then I had no idea of the beauty and skill that went into many vintage wooden sets - a world away from modern cardboard and laser-cut games.'

The wooden puzzle he had discovered was The Music Room, made by English firm Raphael Tuck & Sons in 1920. It is now worth at least £200.

The concept of the jigsaw puzzle began in the mid-18th Century as an educational tool for children - typically 'dissected maps' for learning geography. Discover a map of England with cutout counties made by John Spilsbury in the 1760s and you have a puzzle worth up to £2,000.

The collectable interlocking sets that we recognise as jigsaws today did not arrive until puzzles for adults were introduced around 1900. They were only made possible after the invention of the jigsaw-cutting tool in 1890 - from where the puzzle name is coined.

Previously, puzzles were ' dissections' - not interlinked like modern sets - and were cut using a handheld fretsaw. Wooden jigsaws became increasingly popular and complex during the Edwardian era as a recreational activity for wealthy families. They vanished after the Second World War when cheaper manufacturing processes involving cardboard took over.

David says: 'The earliest 20th Century jigsaws cost 42 shillings - a fortune as the average wage at the time was 15 shillings a week. These were a far cry from modern games, more luxury toys for rich families. Only a few were made and this is what makes surviving sets so valuable.'

Early jigsaws often included silhouettes, also known as whimsies. These were cut-outs of objects and animals within a picture and they greatly add to collectability.

As with other vintage games, an original box is vital if a puzzle is to be rated investment quality. Pictures on boxes were often lacking, however, as the mystery provided added excitement for fans.

David says: 'Jigsaws are a great stress-buster. I reckon they can add ten years to your life. They keep the mind agile.'

Tom Tyler, 70, of Ipswich, life president of The Benevolent Confraternity of Dissectologists, says: 'There were some fiendishly difficult jigsaws made in the early 1900s and the fine level of craftsmanship has not been bettered to this day. Some of these can cost hundreds of pounds, but they are still a relative bargain compared with other antiques.'

Taken from the Daily Mail, written by Toby Walne

Drabble, who became a bestselling sensation with her debut novel A Summer Birdcage, when she was barely out of university, has been obsessed with puzzles since she was a girl. This new book of hers, The Pattern in the Carpet, describes itself as a personal history with jigsaws.

University of Bath researchers have found people approach jigsaws in a number of different ways - and if two strategies clash, there can be trouble.

This can lead to subversive acts such as hiding the last piece - to enable that person to be the winner.

The study into collaboration said people ranged from border obsessives to opportunistic jigsaw puzzlers.

The study, published in the journal ACM Transactions on Computer-Human Interaction and funded by the Engineering and Physical Sciences Research Council, will aid the development computer software that can help people collaborate on work projects.

The researchers said examining how people tackle jigsaws, alone and with others, can give clues as to how people behave in such situations.

Hoarders

People were asked to complete a 120-piece jigsaw, either alone or in a group and videoed as they did so.

Extreme behaviour was observed. Players were seen refusing to allow a fellow player to touch their part of the jigsaw and squabbling over access to pieces.

People were also seen shielding parts of the completed puzzle, hoarding piles of pieces and hiding the picture on the lid from others.

The researchers found that 'border obsessives' focus exclusively on sorting through the entire stock of pieces for the sole purpose of completing the border before concentrating on the rest of the puzzle.

Opportunists, in contrast, are much more creative in their approach, sorting piles on more complex criteria and completing the puzzle using a range of different methods, such as from the top of the picture down to the bottom, or by concentrating on a major component of the picture depending on the pieces they pick up.

Opportunists fared better when completing a jigsaw alone. Border obsessives tended to dominate in groups by controlling decisions and behaviour.

Dr Hilary Johnson from the Human and Computer Interaction Laboratory at the University. said: We are most interested in how both the activity and people's behaviour changes when they collaborate on an activity.

A person's jigsaw strategy closely reflects both their personality and level of skill, and although they may not be as extreme as opportunist or border obsessive, they frequently share behaviour with one of these two extremes.

She added: The strategies people employ to construct a jigsaw on their own can alter dramatically depending on their leadership skills and force of personality when they have to work with someone else.

This is especially so if the person they are working with has a completely contrasting style.

Help or hinder

The team will now develop a simple computer programme to test some of the theories they developed based on the research they have already carried out.

Dr Johnson said: Understanding how people collaborate is a very difficult task. There are all sorts of complex interactions at work, such as how well people know each other, their personality, their underlying leadership skills and so on.

We look for a range of signals in their conversation, their body language and gestures as well as how they plan, negotiate, help and hinder one another in performing the task.

By uncovering the frameworks people use to collaborate on computer-based activities we can use the information to develop software that will help people collaborate more effectively.