But the methodology that underpins the star system often escapes them.

Now Markus Luthe, President of the European Hotelstars Union, has dispelled some of the mystery that surrounds the famous star ranking systems across Europe.

Mr Luthe explained that across Europe 21 nations use a common classification system which rates hotels with stars.

Members of the Hotelstars Union classify their hotels based on the exact same set of criteria - also known as the 21 HOTREC principles.

Mr Luthe said: "Each criterion is assigned points based on its significance, ranging from 1 to 20 points.

"There is a list of mandatory criteria for each category, and additional criteria that can be used to gain more points."

“Meeting the minimum criteria alone is not enough to achieve a star category. Hotels that meet all the mandatory criteria in their category and offer an exceptional level of service are awarded the "Superior" suffix."

Mr Luthe revealed that a hotel could achieve up to 4 stars without a restaurant on site.

HOTREC member countries have agreed to classify their hotels exclusively within the established five-star scale.

Mr Luthe was sceptical of any hotel that claimed to have six or seven stars.

He said that hotels that claims to have above five stars were engaged in "advertising".

The veteran operator said that anything above and beyond five stars was not based on an official catalogue.

He warned travellers that this type of grading: "Would deprive the consumer of security rather than providing additional transparency.”

He explained that any hotel that claimed to have a star ranking not officially awarded to it would by contacted and asked to remove it.

He added that if the hotel refused to comply they would be reported to relevant trading and consumer bodies.

Mr Luthe said that the existing HOTREC system was "one of the main criteria for choosing a hotel."

According to HOTREC, hotel stars remain as one of the most frequently used search filters on booking portals.

Tom Duffy