It is often said that politeness costs nothing. In fact, it seems that a little more courtesy could save businesses £5billion every year.

Frequently hearing the phrase "thank you" or "well done" means the same to staff as a modest pay rise, researchers say.

Praise and encouragement also makes employees more likely to work hard and stay in their jobs, saving on the cost of finding replacements.

A third of 1,000 workers surveyed by consulting firm White Water Strategies said they did not get thanked at all when they did well - and a further third said they were not thanked enough.

In both cases, staff said they felt undervalued, meaning they were less likely to exert themselves and were more likely to look for employment elsewhere.

The net result is around £5.2billion in lost productivity from employees who would raise their game if they felt more appreciated, White Water claimed.

According to the company, praising staff has the same motivational kick as a 1 per cent pay rise - and works out much cheaper for bosses.

Three out of four employees said that regular acknowledgement by their bosses was important to them, but only a quarter said they were actually given as much praise as they felt they needed.

The survey found that those in blue-collar and manual jobs were less likely to be given any recognition for doing well.

In regional terms, Scottish staff felt most undervalued. Four out of ten workers said they were never thanked and eight out of ten said they would like more praise.

However, workers in the North-East are less impressed by being buttered up by the boss, as only 69 per cent said they felt the need to be told "well done" regularly.

Older employees and women need the most reassurance, according to psychologist Averil Leimon, a director of White Water Strategies.

She said that words of praise did more than create a pleasant place to work - they could even boost profits.