Here we go...
From
https://www.thomascook.com/privacy-policy/
Your right to access any personal data we hold:
The Data Protection Act 1998 (the “Act”) gives you the right to check that your personal data is being processed lawfully (“subject access right”). Your subject access right can be exercised in accordance with the Act. Any subject access request must be made in writing to: The Data Protection Manager, UK Legal & Compliance Dept., Thomas Cook Retail Ltd, Thomas Cook, Westpoint, Peterborough Business Park, Lynch Wood, Peterborough, PE2 6FZ, and may be subject to a fee of £10 to meet our costs in providing you with details of any personal data we hold about you.
Write in giving details of the flights you think you were on and a cheque for £10 and you should get the information you require, if Thomas Cook still hold that data.