1808 Thomas Cook is born on 22 November in the village of Melbourne in Derbyshire.
1834 John Mason Cook is born on 13 January in Market Harborough, near Leicester.
1841 Thomas Cook organises his first excursion, a rail journey from Leicester to a temperance meeting in Loughborough. On Monday 5 July a special train carries some 500 passengers a distance of 12 miles and back for one shilling.
1845 Thomas Cook conducts his first trip for profit. It is a railway journey to Liverpool from Leicester, Nottingham and Derby. Fares are 15/- first class and 10/- second class, with a supplementary charge for travelling by special steamer to North Wales
1846 Thomas visits Scotland for the first time. A party of about 350 people travels from Leicester to Fleetwood, then to Ardrossan by steamer, and onwards by rail to Glasgow. Special trips are made to Edinburgh, Stirling and Ayr.
1851 Thomas Cook promotes trips to the Great Exhibition in Hyde Park. More than 150,000 people from Yorkshire and the Midlands, including a party of 3,000 children from Leicester, Derby and Nottingham, travel to London under his arrangements.
- The Excursionist is published for the first time as Cook's Exhibition Herald and Excursion Advertiser.
1855 Thomas Cook's first continental tour. He personally conducts two parties from Harwich to Antwerp, then on to Brussels, Cologne, Frankfurt, Heidelberg, Strasbourg and, finally, to Paris for the International Exhibition.
1863 Thomas Cook conducts his first party of 62 people to Switzerland, via Paris. A journal of this trip, kept by Miss Jemima Morrell, survives in the Thomas Cook Archives.
1864 John Mason Cook, aged 30, joins his father in business.
1865 Thomas Cook opens an office in Fleet Street, London, the upper floor of which is used as a Temperance Boarding House.
1866 John Mason Cook personally conducts the first American tour.
1868 Thomas Cook introduces a system of hotel coupons (which he had tested the previous year) in an attempt to get fixed prices for accommodation at selected hotels in all major cities.
1869 Thomas Cook escorts his first party to Egypt and Palestine.
1871 Thomas Cook & Son becomes the official name of the firm when John Mason Cook joins his father as a business partner.
1872/73 Thomas Cook organises and leads the first round-the-world tour. He is away from home for 222 days and covers more than 25,000 miles.
1873 Thomas Cook & Son opens its new head office at Ludgate Circus, London. Also the first edition of Cook's Continental Time Tables & Tourist's Handbook is published.
1874 Cook's Circular Note, an early form of the travellers cheque, is launched in New York.
1878 A distinct Foreign Banking and Money Exchange Department is established.
1879 John Mason Cook becomes 'sole managing partner' of the company.
1884 The relief force sent to rescue General Gordon from Khartoum is conveyed up the Nile as far as Wadi Halfa by Thomas Cook & Son.
1892 Thomas Cook dies, aged 83.
1898 Kaiser Wilhelm II's tour of the Holy Land is organised by John Mason Cook and his son Frank.
- John Mason Cook dies suddenly at the age of 65. The company passes into the hands of his three sons: Frank, Ernest and Thomas ('Bert').
1908 Thomas Cook & Son issues its first winter sports brochure.
1919 Thomas Cook & Son is the first travel agent to offer pleasure trips by air.
1922 Thomas Cook & Son organises the first tour to cover the whole length of the African continent. The tour lasts five months and includes a one-month safari.
1924 Thomas Cook & Son Ltd is incorporated.
The head office of Thomas Cook & Son Ltd moves to Berkeley Street in London's Mayfair district.
1927 Thomas Cook & Son Ltd organises the first personally-conducted air tour - from New York to Chicago for the Dempsey-Tunney heavyweight boxing contest.
1928 Frank and Ernest Cook, the two surviving grandsons of Thomas Cook (Bert having died in 1914), retire, selling the business to the Compagnie Internationale des Wagons-Lits et des Grands Express Européens.
1939 Holidays by air on specially chartered aircraft to the French Riviera are included in Cook's summer brochure for the first time.
1948 Thomas Cook & Son Ltd becomes state-owned under the British Transport Holding Company.
1959 Thomas Cook introduces to business clients a new worldwide credit scheme for travel and related services.
1966 Thomas Cook's 125th anniversary.
1972 Thomas Cook is privatised and bought by a consortium of Midland Bank, Trust House Forte and the Automobile Association.
1974 Thomas Cook launches a customer protection guarantee in UK retail shops.
1977 Thomas Cook opens its new administrative headquarters at Thorpe Wood in Peterborough.
- Midland Bank buys out Trust House Forte and the Automobile Association to become the sole owners of Thomas Cook.
1980 Thomas Cook Travel Book Awards first presented.
1981 Thomas Cook introduces 'Holidaymaker', a private viewdata system allowing travel agents to access directly Thomas Cook Holidays reservation system.
1982 Thomas Cook purchases Rankin Kuhn Travel Ltd
1986 Airfare Warehouse is launched.
1989 The long-standing agreement with Wagons-Lits comes to an end and the development of a new worldwide network begins.
1990 Thomas Cook becomes the world's leading foreign exchange retailer when it acquires the retail foreign exchange operations of Deak International Inc.
1991 Thomas Cook celebrates its 150th anniversary. A 34-day round-the-world trip is arranged to commemorate this occasion, and a re-enactment of the first railway excursion from Leicester to Loughborough takes place on 5 July.
1992 Westdeutsche Landesbank, Germany's third largest bank, and the LTU Group, Germany's leading charter airline, acquire the Thomas Cook Group from Midland Bank.
1994 Thomas Cook acquires Interpayment Services Limited, the travellers cheque subsidiary of Barclays Bank plc, to become the world's largest supplier of travellers cheques outside the United States.
- Following a major review of its global activities, Thomas Cook sells its travel management business to American Express.
1995 Westdeutsche Landesbank acquires LTU's 10% share of the Thomas Cook Group, making Thomas Cook a wholly-owned subsidiary of WestLB. Thomas Cook launches its own Internet site.
1996 Thomas Cook acquires Sunworld, the UK and Ireland's fourth largest short-haul tour operator, and Time Off, the specialist European city breaks tour operator.
- Thomas Cook announces plans to form the world's largest leisure travel alliance with the American Automobile Association (AAA), subject to US regulatory clearance.
1997 Thomas Cook On-Line is launched, making Thomas Cook the first UK retail travel agency to offer customers a way to buy holidays, foreign currency, travellers cheques and guidebooks over the Internet.
1999 The European Commission approves the merger of Thomas Cook and Carlson Leisure Group's UK travel interests.
2002 Thomas Cook Airlines Belgium begins operating in March, serving holiday destinations in the Mediterranean and on the Canary Islands with a fleet of five Airbus A320 aircraft.
Thomas Cook is set to become the first fully international leisure brand. The Thomas Cook brand - hitherto used as the company's name as well as for its sales and service activities - will in future appear in all markets and on all levels of the travel-related value chain.
2003/2004.Thomas Cook celebrates 150 years of taking Britain abroad - since the first ever overseas holiday, and launches holidays to Brazil for the first time.
2004 Thomas Cook announces its partnership with the Variety Club of Great Britain as its chosen charity. The relationship involves fundraising activity and Christmas flights for underprivileged, sick and disabled children.
- A new 'dynamic packaging' brand, FlexibleTrips, is launched to enable customers to build their own holidays in store and online.
2005 Thomas Cook UK & Ireland announces its greatest ever profits of £50 million over the financial year
2006 The company announces record profits of £83.3 million and achieves the 'holy grail' of the travel industry, a five per cent profit margin. Thomas Cook is also listed as one of the Sunday Times Top 20 Best big companies to work for.
2007 Thomas Cook becomes part of Thomas Cook Group plc which was formed on June 19th 2007 by the merger of Thomas Cook AG and MyTravel Group plc.
-In December Thomas Cook UK & Ireland becomes listed on the London Stock Exchange for the first time.
2008 Thomas Cook Group acquires Canada’s TriWest Travel Holdings, French tour operator Jet Tours, and UK independent travel companies hotels4u, Gold Medal and Elegant Resorts.
2009 Thomas Cook’s majority shareholder, Arcandor AG places its remaining shares on the stock market, resulting in 100% of the Group’s shares being freely floated on the London Stock Exchange.
2010 Following the earthquake in Haiti, Thomas Cook Group helps the Disasters Emergency Committee, UNICEF and various charities to carry aid and relief personnel out to the affected area.