While many budget airlines are announcing new routes, additional hubs and discount promotions every week, it still pays to investigate what you are really being charged when you book a ‘cheap' flight. In the wake of Ryanair's announcement that it intends to charge passengers a ‘pound to spend a penny', the ‘Metro' newspaper investigated a number of charges added to cheap flights, including fees for credit and debit card bookings, charges for hand and hold luggage, additional check-in fees and even the price of in-flight food. Surveying five of the UK's most popular budget airlines – Aer Lingus, bmibaby, easyJet, Ryanair and Thomson Airways – the ‘Metro' found that there were a number of additional charges on top of the initial ticket price. Credit and debit card charges are a common hazard when buying items online, particularly when booking a ‘budget' flight. Thomson Airways do not charge any debit card booking fees, although Aer Lingus and Ryanair charge over Â£4 per person per flight. For credit card bookings, Thomson Airways charge a 2. 5% fee, while none of the other budget airlines charge less than Â£3. 50 per booking. Ryanair charge the highest fees at Â£4. 75 per person per flight. None of the airlines featured charge a fee for hand luggage, however their allowances for hold luggage differ wildly. Ryanair and Thomson Airways offer a 15kg hold luggage allowance, while easyJet offers the largest allowance of 32kg. Priority boarding can be a useful extra for passengers who want to avoid the rush for seats during boarding. EasyJet charge the most for their Speedy Boarding scheme, while priority boarding on Ryanair flights costs Â£1. 90 online or Â£2. 85 at the airport/call centre. Bmibaby charge a nominal fee, while Aer Lingus and Thomson Airways allocate their seats at no extra charge. Editor of ‘Which? Holiday', Lorna Cowan, said: 'We're disappointed to see major budget airlines introducing charges for services that were once included in the cost of a ticket. 'Ryanair's charge to use its check-in desk is especially unfair. The only way to avoid this is not to check luggage into the hold. . . Although the airlines view these services as optional, who would go on a week's holiday without checking a bag into hold?'