While many companies gather data about their customers, it has been suggested that they could get more out of this information by managing it more effectively.

According to the Chartered Institute of Marketing (CIM), firms should make sure their records can provide detailed information from a long time ago and see how long it has been since a customer made a purchase.

"Keeping your database up to date and alive, and paying attention to return mail, can be worthwhile," said Ray Jones, a spokesperson for CIM.

"It all comes back to good database management. If you have a customer who's been with you since two or three years ago, there's no harm in ringing them up."

He added that this may be especially useful for small firms who should be doing all they can to ensure previous clients return to use their products or services again.

"If you're a small SME, there's nothing wrong with everyday ringing six old customers and asking them if they'd like a new service," Mr Jones said, adding that the importance of a customer base is shown by the way it is viewed as an asset when firms are purchased.