The poll of 3,500 people rated Trailfinders as the best holiday company, with a customer score of 97%.

But Shearings, Thomas Cook, and Newmarket Holidays sat at the bottom of the table with below average scores of 62%, 60% and 57% respectively.

Ian Ailles, CEO of mainstream for Thomas Cook UK & Ireland, said: "It"s impossible to see how this survey offers consumers a like-for-like comparison when Which? is comparing tour operators with completely different products - from specialist, tailored itineraries to popular mass market holidays - that appeal to completely different customers.

"Our own more meaningful survey - which is 145 times larger than the Which? survey - showed that 94% of our customers rated their summer holiday in 2011 as excellent or good."

Simon Hibbs, managing director of The Newmarket Group, said: "I would like to express my surprise with our company's 'apparent' poor performance in the Which? report.

"We take all consumer feedback seriously, but this particular survey is somewhat flawed since our rating was based upon a sample size of just 42 people (despite the fact that we took 227,000 customers on holiday last year).

"Our company has been trading successfully for nearly 30 years, has built a hard-earned reputation for value-for-money, has a 'repeat-factor' of over 40%, and last year was voted 'Best Coach Operator' by the public at the British Travel Awards.

"To be portrayed in this way, on the basis of 42 comments, is simply not a true reflection of the regard in which Newmarket is held by the vast majority of our customers."

In the Which? survey, published this week, activity holiday specialists HF Holidays (94%), Inntravel (94%) and Exodus (90%) also performed well, helping to make up the top five companies, along with Audley Travel (93%).

Lorna Cowan, editor of Which? Travel, said: "The travel industry has faced some turbulent times in recent years so we were thrilled to see so many companies performing well in our survey and delivering the high standards of customer service holidaymakers expect."