Queen Elizabeth and Prince Philip will attend a service to mark the 100th anniversary of the Order of The British Empire.
The 91-year-old royal is the sovereign of the order, which King George V launched in 1917 to recognise the effort of World War I, and the monarch’s 95-year-old husband is the Grand Mater.
They will be joined by over 2,000 guests who have been honoured with a knighthood, CBE, OBE or MBE at a service at St Paul’s cathedral in London.
The event is held every four years, the last being in 2012.
Nowadays celebrities who have contributed an outstanding amount to their craft or through charity work are recognised with knighthoods.
Sirs include the likes of Tom Jones, Rod Stewart, Paul McCartney and Sean Connery.
Dames include actresses Helen Mirren, Judi Dench and Barbra Windsor.
It will be one of the last duties the Duke of Edinburgh attends to before he retires.
The Duke’s decision was announced in an official statement earlier this month.
It read: "His Royal Highness The Duke of Edinburgh has decided that he will no longer carry out public engagements from the autumn of this year. In taking this decision, The Duke has the full support of The Queen.
"Prince Philip will attend previously scheduled engagements between now and August, both individually and accompanying The Queen. Thereafter, The Duke will not be accepting new invitations for visits and engagements, although he may still choose to attend certain public events from time to time.
"The Duke of Edinburgh is Patron, President or a member of over 780 organisations, with which he will continue to be associated, although he will no longer play an active role by attending engagements. Her Majesty will continue to carry out a full programme of official engagements with the support of members of the Royal Family."
Queen and Prince Philip to attend Order of The British Empire service
