Cunard has updated its dress codes by switching from ‘formal’, ‘semi-formal’ and ‘elegant’ casual to just formal and informal, to strengthen its commitment to special occasion dressing.

The changes, where four or five evenings will be designated as ‘informal’, requiring jackets but with ties as optional, while two or three nights will be formal, will take effect before Queen Mary 2, Queen Elizabeth and Queen Victoria set out on their main sailing seasons in April and May 2013.

The cruise line said that research with existing passengers and luxury travellers had prompted the brand to make more of a distinction between formal and informal dressing by having formal evenings three times a week on its transatlantic crossings and twice each week on sailings to the Mediterranean, Scandinavia and beyond.

However, in response to growing travel trends, Cunard is making an adjustment to its advice on dress codes on other nights. Along with two or three formal nights each week, there will be four or five ‘informal’ evenings where jackets are required but ties will now become optional.

Peter Shanks, Cunard’s president and managing director, told Travel Weekly they had decided to clearly designate which dinners were formal and which weren’t, unlike what other cruise lines were doing, which was having “formal optional, which is like being half pregnant”.

“The glamour of dressing to the nines is a hallmark of travelling with Cunard, and distinguishes us from the mass of cruise operators where dressing up has become a thing of the past,” said Shanks.

“In a world where everything seems to tend towards the casual, Cunard is proud to give passengers the opportunity to put on their best bib and tucker and really shine.

“Dressing up heightens anticipation and brings an extra special sense of occasion to an evening at sea. Our passengers tell us it makes all the difference to their enjoyment of a big night out on board.

“Formal nights are a chance for the ladies to sparkle in cocktail dresses or full-on evening gowns, while for the gentlemen, dinner jackets – or tuxedos or dark suits – always bring a touch of sharp, 007-type style to the occasion.”

Passengers opting out of evening wear in formal nights will be welcome in the ships’ main buffet restaurants and in the adjoining Winter Garden or Garden Lounge bars, but not in other areas of the ship, out of respect for their fellow guests.

By day, smart casual remains the style of choice among Cunard’s passengers, as in a five star hotel ashore.