(ShareCast News) - Travel agent Thomas Cook swung to a third quarter profit and it expects full-year earnings to grow on a constant currency basis.In the three months to 30 June, the FTSE 250 group posted profits of £3m from a £50m loss in the corresponding period in 2014, marking its 12th consecutive quarter of improved profitability.Revenue edged 0.2% higher to £1.95bn, while the company said it had sold 78% of its 2015 summer holidays, unchanged from last year, and the number of bookings improved across most markets.The impact from the currency headwinds on annual profit is expected to be around £25m, while cancellations of holidays to Tunisia in the wake of a resort attack last month will also weigh on results."We've delivered a good performance in the third quarter, executing on our strategy and improving our underlying operating profit and cash flow in spite of weaker market conditions," said group chief executive Peter Fankhauser."Customer demand for our differentiated product continues to grow, our focus on quality is achieving positive results, and our digital progress is encouraging."Analysts at N1+ Singer said that despite the negative impact from forex and events in Greece and Tunisia, the group's turnaround remained on track.Thomas Cook shares were up 0.16% to 126.60p at 1053 BST on Thursday.