Prince William and his cousins rally round to step in for King Charles as he continues cancer treatment

Prince William led the royal charge yesterday, braving the wet and windy conditions as community stalwarts were welcomed to a rain-soaked Buckingham Palace garden party.

The Prince of Wales was accompanied by the Duke and Duchess of Gloucester, representing the King at the third gathering of the year at the royal headquarters. As they stepped out onto the palace steps overlooking the rear gardens, they were greeted by a sea of umbrellas while the national anthem played.

Approximately 8,000 guests were invited to honour the work of volunteers, military personnel and members of the public.

During the garden party, William mingled with guests from various patronages of both the Prince and Princess of Wales, military affiliations and so-called "passion projects". This includes his project to combat homelessness in the UK, Homewards, RAF Valley where he served as a search and rescue pilot for three years from 2010 to 2013, Swim England, and tenants across Duchy of Cornwall sites.

Royal aides revealed that William personally invited other "young members" of the Royal Family to join him for the day, including Princesses Beatrice and Eugenie, Zara and Mike Tindall, and Peter Phillips. King Charles and Queen Camilla, who hosted the first two garden parties this year, including one last week celebrating the creative industries, were absent from yesterday's event, reports the Mirror.

The King, 75, is currently undergoing weekly cancer treatment in London and is expected to return to duties later this week.

The Prince of Wales hosted a garden party to celebrate community heroes last May, alongside his wife the Princess of Wales. Kate, 42, has since taken a leave of absence from royal duties after revealing in a public statement that she had been diagnosed with cancer.

The future Queen is currently undergoing preventative chemotherapy treatment and will not return to duties until her doctors give her the all-clear.

Despite her health struggles, Kate was hailed as the "driving force" behind a new report that could potentially boost the UK economy by £45.5billion annually. The princess has been closely following the work of chief executives she convened last year as part of a Royal Foundation Business Taskforce for Early Childhood, aimed at promoting business action on the importance of early childhood development.

It's been disclosed that Kate has been kept fully informed throughout the process and the development of the task force's work and had seen the report in advance. However, Kensington Palace emphasised that the launch of the report does not indicate the princess's return to work.

A report released today from eight leading UK companies, pinpoints five areas where businesses of all sizes can support children under five and their caregivers. Last year, Kate assembled the Business Taskforce to contribute to her "vision for the future" concerning early years development in children.

Get the latest celebrity gossip and telly news sent straight to your inbox. Sign up to our daily Showbiz newsletter here.