(ShareCast News) - Thomas Cook had a positive end to the financial year, with an encouraging start to winter trading.The FTSE 250 listed travel company released a trading statement on Thursday ahead of its financial year end.It announced 2015 summer holiday sales were 91% sold - in line with expectations and at the same level as 2014.Northern Europe also enjoyed a boost after a slow start to the year, with demand accelerating substantially and summer 2015 holidays 99% sold.The company said it was encouraged by strong booking and pricing trends for both winter 2015/16 and summer 2016 seasons.Winter holidays are now 39% sold and all of the group's major source markets are ahead of last year in terms of booking volumes.Demand has continued to grow for its differentiated holidays, particularly to its own-brand hotels.Thomas Cook chief executive Peter Fankhauser said summer trading progressed well "despite the impact of external shocks in certain destination markets, as previously announced".He said progress has been made over the last three years to transform the business, and the focus is moving to the next phase."The next phase of transformation will aim to better integrate our businesses across geographies, with a higher quality and more focused holiday offering delivered through our new operating model."With the benefit of our strong brands and through our absolute focus on customer needs, I am confident that this strategy will lead to an even better holiday experience for our customers, further improving our growth and profitability, and increasing returns to shareholders."Hargreaves Lansdown Stockbrokers equity analyst Keith Bowman said despite clear challenges, the group is again reporting progress. "For now, and with current geopolitical and currency challenges weighed against an undemanding valuation, analyst consensus opinion currently signifies a strong hold."The group's full results for the year ended 30 September 2015 will be announced on 25 November.