Queen Letizia of Spain walks arm-in-arm with husband King Felipe VI as they pay tribute to his uncle King Constantine in Windsor

Queen Letizia of Spain put on an elegant display as she joined her husband King Felipe VI at the memorial service for the late King Constantine of Greece at Windsor Castle on Tuesday.

The European monarch, 51, looked solemn in a navy knee-length dress, which she paired with matching heels and a shawl.  

The mother-of-two arrived arm in arm with her husband King Felipe, whose mother Queen Sofia, 85, is Constantine's older sister. 

Felipe himself also cut a stately figure in a black long coat, also adding a formal grey scarf, as the couple put on a united display.  

The royals had travelled over from Spain for the occasion, with Letizia adding a black scarf to cope with the cold British weather. 

Queen Letizia of Spain put on an elegant display as she joined her husband King Felipe VI at the memorial service for the late King Constantine of Greece at Windsor Castle on Tuesday

The European monarch, 51, looked solemn in a navy knee-length dress, which she paired with matching heels and a shawl

Once inside St George's Chapel, the couple sat with King Juan Carlos of Spain and Princess Benedikte of Denmark.

King Felipe last met with the British royals when he attended the Wimbledon men's final between Carlos Alcaraz and Novak Djokovic - and both Letizia and Felipe were guests at the coronation last year. 

The British royals last hosted the Spanish royal family for a state visit in 2017.  

Today's service will be attended by several of the ruling houses of Europe. 

The Prince of Wales, 41, was expected to give a reading at his late godfather's service but pulled out at the last minute due to personal reasons.  

William called the Greek royal family to apologise, while Kensington Palace confirmed the Princess of Wales was 'doing well' as she continues her abdominal surgery recovery at home. 

Today's service at St George's Chapel is being held in honour of King Charles' close friend and second cousin Constantine II, the former ruler of Greece. 

The last King of Greece died on January 10 last year at the age of 82 after months of illness - more than 50 years after he was exiled in a military coup.

The late King - who was the only son of King Paul and Queen Frederica - was also the Duke of Edinburgh's nephew and Prince William's godfather.

The mother-of-two arrived arm in arm with her husband King Felipe, whose mother Queen Sofia, 85, was Constantine's older sister

The royals had travelled over from Spain for the occasion, with Letizia adding a black scarf to cope with the cold British weather

The royal couple put on a very united display at the occasion, which was attended by high profile royals

The couple had travelled over from Spain for the occasion to attend the thanksgiving service

Once inside St George's Chapel, the couple sat with King Juan Carlos of Spain and Princess Benedikte of Denmark

Prince Andrew was spotted arriving for the thanksgiving service along with his ex-wife Sarah Ferguson.

It is understood, the Duke of York is attending as a member of the British Royal Family and was invited by the Greek Royal Family. 

King Constantine's funeral was attended by Princess Anne and her husband Vice Admiral Sir Timothy Laurence in January 2023. 

Constantine became King of Greece in 1964 but was ousted from the throne when the monarchy was abolished in 1973.

King Charles is not expected to attend his memorial in Windsor after drawing back from public life following his cancer diagnosis.

Camilla's role in the service will see her again taking the reigns as she works to take the pressure off her husband.

Members of the Royal family have rallied around the King, with Prince William returning to duties after spending time caring for his wife Princess Kate.

The couple cut solemn figures as the thanksgiving service began 

Seated in front of the Spanish royals were Princess Maria-Olympia of Greece, Prince Achilleas of Greece, Carlos Morales and Princess Tatiana of Greece (pictured left to right)

In a separate health scare, the Princess of Wales had been admitted to The London Clinic for planned abdominal surgery, and she will not be able to perform any royal engagements until at least Easter.

Last month the Greek royal family put on a sombre display as they attended a memorial service to mark one year since the death of King Constantine.

He died 'of a stroke', local media reported, following several hospital admissions in the months before.

High-profile royals, including Constantine's son Crown Prince Pavlos and widow Queen Anne Marie, attended a private ceremony at the former summer palace of Tatoi, just outside Athens.