Workers have said "get knotted" to ties as a growing number of firms allow their staff to dress down, new research shows.

The casual approach to wearing clothes has paid dividends, with four out of five companies reporting increased productivity among staff if they did not have to wear formal clothes. Nine out of 10 adopted a "no tie" policy as part of a general relaxing of dress codes during the current heatwave, a survey of 560 employers by employment law firm Peninsula showed.

Most of those questioned said they regularly held "dress down days", with four out of five saying that these special events boosted productivity.

Peter Done, managing director of Peninsula, said the findings revealed a growing trend across British industry.

"The popularity of dress down days and relaxed attitudes towards dress code have soared in recent years. The traditional standards of attire for work are ever diminishing and this has become apparent during the recent heatwave that has swept through the UK's workplaces.

"Traditional conventions within which business is conducted are being challenged, and are constantly changing to meet the demands of the growing global environment."