Twenty-two UK airports are preparing to let passengers take more than one piece of hand luggage on flights from Monday, to coincide with extra security checks.
Every piece of hand luggage will still have to be checked by scanners
Heathrow, Manchester, Glasgow and Edinburgh are among the airports where two luggage pieces will be permitted.
But some restrictions remain at Gatwick and other airports which have not met government requirements for the relaxation of the one-bag rule.
Some airlines, including Easyjet, are also keeping the one-bag limit.
From 7 January, the Department for Transport says, travellers can carry more than one piece on board, providing the airport has installed improved security scanners, and depending on their airline's policy.
Source: Department for Transport
Most of the UK's major airports, including Heathrow, Manchester and Birmingham, now have the scanners.
Some, including Glasgow and Edinburgh, only received the go-ahead in the last few days, but several, among them Bristol, Luton, Leeds/Bradford and Liverpool John Lennon airport, have yet to meet the standards.
They still have to prove they can cope with extra cabin bags without compromising security.
At Gatwick, Britain's second busiest airport, only passengers using the South Terminal for connecting flights from Monday will be able to travel with more than one piece of hand baggage if their airline allows.
BAA, which runs Gatwick, says restrictions will remain in place at the North Terminal while engineering works continue to bring the airport up to standard.
However, from 11 February passengers using the North Terminal on connecting flights will also be able to take more than one piece of cabin luggage.
Size limits on liquids and cabin baggage will still apply and airlines can place their own restrictions on the amount of hand baggage that can be taken in to their aircraft.
The government has stressed it is up to passengers to check hand-luggage policy with individual airlines.
British Airways will allow two pieces of hand luggage per passenger.
Virgin Atlantic will allow one piece of cabin luggage per passengers in Economy and Premium Economy Class (plus laptop, handbag or similar); and two pieces of luggage per passenger travelling first class.
This is the policy the airline operated before the restrictions came in.
Easyjet is keeping the one-bag rule in place because it says too many airports still have the rule to justify abandoning it.
Easyjet's Chief Executive Andy Harrison said: "There is massive scope for customer confusion in an environment where UK airports are adopting different policies.
"The only way to maintain a simple and standard policy is to maintain our one bag policy."
A spokesman for Ryanair could not be contacted for comment.
The dimensions of hand luggage must not exceed 56cm x 45cm x 25cm (22in x 17.7in x 9.8in approx), including wheels, handles and side pockets. This is equivalent to the size of a small roller suitcase.