Duchess of Gloucester is sombre as she attends the Field of Remembrance at Westminster Abbey in place of Queen Camilla

The Duchess of Gloucester has paid tribute to fallen soldiers in a poignant ceremony at Westminster Abbey's Field of Remembrance.

Birgitte, 78, attended the event in place of Queen Camilla , who had to pull out due to falling ill with a chest infection.

She opted to wear sombre colours sombre dark tones as she paid her respect to fallen soldiers ahead of Armistice Day on Monday.

Queen Camilla, who is Patron of The Poppy factory, normally attends the annual commemoration at Westminster Abbey, now marking its 96th year.

The event, which has been held since 1928, serves to provide former service personnel and members of the public with a meaningful occasion to plant poppy memorials in honour of those who have sacrificed their lives in the Armed Forces.

While attending the event, the Duchess of Gloucester laid a Remembrance cross.

She looked appropriately sombre as well as stylish in her dark grey coat, which she paired with a navy hat, and black suede knee high boots.

The Duchess' appearance comes days after an announcement that Queen Camilla had to reluctantly withdraw from the annual opening of the Field of Remembrance falling ill with a chest infection.

It's understood that the 77-year-old is recovering at home in Wiltshire and is being monitored by doctors.

Due to her illness, Her Majesty has had to reluctantly withdraw from the annual opening of the Field of Remembrance at Westminster Abbey this Thursday.

Camilla not attending the event was seen as a sign of how poorly she is feeling, as the engagement is a duty she takes extremely diligently, as the daughter of decorated war hero Major Bruce Shand, who earned two military crosses in the Second World War for his bravery.

Camilla also had to cancel her appearance at a reception at Buckingham Palace in honour of the nation's Olympic and Paralympic today.

King Charles will still attend, accompanied by his sister Princess Anne.

However, an update issued by the Palace yesterday revealed that the Queen is expected to return to work as soon as next week.

Camilla will host a reception for authors shortlisted for this year's Booker Prize at Clarence House after taking some time out while under the weather.

Buckingham Palace announced on Tuesday that the Queen, who has just completed a mammoth tour of Australia and Samoa with King Charles, was cancelling her forthcoming engagements due to a chest infection.

However, the known bookworm and literature lover is set to return to her duties next Tuesday to host the reception - after news of her condition caused concern among royal fans.

The update comes after a year of health troubles for the Royal Family, with both the King and the Princess of Wales being diagnosed with cancer.

A Buckingham Palace spokesman said: 'Her Majesty The Queen is currently unwell with a chest infection, for which her doctors have advised a short period of rest.

'With great regret, Her Majesty has therefore had to withdraw from her engagements for this week but she very much hopes to be recovered in time to attend this weekend's Remembrance events as normal.

'She apologises to all those who may be inconvenienced or disappointed as a result.'

Camilla also hopes she will also be well enough to attend this weekend's Remembrance events, including the ceremony at the Cenotaph on Sunday.

The Queen returned to the UK on October 30 after a busy official overseas tour to Australia and Samoa with the monarch, which included a three-day stopover in India on the way back.

MailOnline understands that there is 'no cause for alarm' and it is just one of the many 'seasonal bugs' that can be picked up at this time of year, especially given her international travel.

Camilla and the King have also just undertaken a gruelling 11-day, 30,000-mile round trip, partly on commercial airlines.

The Queen broke up her journey by visiting an Ayurvedic spa in India for a few days on the way out, and again on the way home for three days, this time with the King.

No further details regarding her illness or treatment have been released, but Camilla is understood to be under doctors' supervision.