Wardle founded his agency more than 40 years ago after a long and varied career, which included running a fleet of local buses in Staffordshire.
ITT Chair Steven Freudmann shared the news in an email to ITT members on Wednesday (2 September).
Wardle was an ITT conference regular, and was known for preceding his questions with a booming "Doug Wardle, Wardle Travel!".
"Our dear friend and great ITT supporter, Doug Wardle, died this morning aged 92," said Freudmann. "Our thoughts are with his wife, Ruth and his son, Chris. Conferences won't be the same without, 'Doug Wardle, Wardle Travel!'."
Last year, Wardle and his family pledged £10,000 to help a new generation of talented travel industry entrants attend the conference and benefit from the knowledge and expertise within the ITT.
'Great supporter'
In a separate comment provided to TTG, Freudmann said: "I am desperately sad to hear that my old friend and great supporter of ITT has passed away aged 92.
"Doug was a member of ITT for more than 40 years and last year established the Doug Wardle ITT Bursary enabling ITT students to attend our annual overseas conference.
"Wardle Travel was established in 1983 and over the years Doug held many positions at Abta including Chair of the Abta Midlands region."
Wardle's passing quickly follows that of another ITT stalwart, political advisor Lord Peter Snape, who hosted more than 100 events for the ITT in the Houses of Parliament.
Did you know Doug Wardle? Work for Wardle Travel? Spend time with him at an ITT conference? Share your memories in the comments below.