For the second time in a year, Ryanair is changing its cabin-baggage policy – dramatically reducing the amount passengers can carry without paying extra.

Europe’s biggest budget airline currently allows passengers to take one large and one small cabin bag without paying. But from November, the limit is cut to one midsize bag.

The overall volume allowed without paying falls by almost two-thirds from 58 litres to 20 litres.

The new policy will apply for all flights from 1 November. But anyone with bookings from November onwards can either accept the new policy or cancel for a full refund.

Passengers who want to bring a wheelie-bag weighing no more than 10kg must pay £6 for priority boarding, which will allow them to bring it on board, or £8 to check it in.

Ryanair insists the move is not aimed to make more money, but purely to improve timekeeping.

Passengers have only been getting used to the airline’s latest cabin-baggage policy since January. The current rules allow passengers to take two bags through the security checkpoint to the departure gate.

But only travellers who have paid for priority boarding can carry them onto the aircraft. Other passengers’ larger bags are tagged at the gate and placed in the hold.

“Punctuality has been a challenge this year,” said Kenny Jacobs, the airline’s chief marketing officer.

“We’ve flagged for a while that while we love offering two cabin bags, it was creating a problem at the boarding gates. We want to protect our punctuality.”

Speaking exclusively to The Independent, Mr Jacobs said: “The average bag we have in the hold weighs 12.5kg. I think you’ll see a lot of customers now packing a little bit lighter to take advantage of the lower price.”

At present the standard checked bag limit is 20kg, for a price of £25.

It will still be cheaper to pay £6 for priority boarding than to pay £8 for a 10kg checked bag, but the number of passengers allowed to choose priority boarding will be capped at 95 – half the capacity of Ryanair’s Boeing 737s.

The airline claims that only 40 per cent of passengers will be affected, since 30 per cent already buy priority boarding and 30 per cent currently travel with one bag which complies with the new dimensions.

“It’s a new charge, but fares are going down at the same time,” said Mr Jacobs. “This is a fair outcome customers will get used to.”

Passengers will be allowed a bit of “wriggle room” in terms of their free bag; the gauge deployed at the departure gate to check the dimensions is 25 per cent bigger than the maximum size.

Other airlines will be looking closely at the effect of the new rules and the reaction of passengers.

Ryanair’s leading rival, easyJet, currently allows one piece of cabin baggage with no weight limit and a volume of 63 litres.