'Oh god I hate this!’ Grieving King Charles can't escape faulty fountain pen frustration

* The Queen arrives back at Buckingham Palace for final night with entire Royal Family
* King Charles, siblings walk with Queen's coffin in Edinburgh, observe vigil
* Royal reporter Gavin Gray breaks down 'Operation Unicorn' following Queen's passing with Jono and Ben
* King Charles told Prince William to reach out to his brother Prince Harry an hour before reunion
* Meghan Markle’s awkward moment with royal aide has left fans divided

We all have moments of frustration – even the King of England.

King Charles III lost his cool after a faulty fountain pen spilled ink onto his hands during a signing ceremony in Northern Ireland.

Not only does the monarch have to carry the weight of the loss of his mother Queen Elizabeth – who passed away peacefully last week – but he has to continue on with royal duties.

Already annoyed after realising he had put the wrong date on the official signing ceremony – September 12 instead of September 13 - at Hillsborough Castle, the royal family's home in Northern Ireland, but became incredibly frustrated by the ink.

"Oh God I hate this," Charles can be heard in the video of the signing, rising to his feet and handing the pen to his wife.

"Oh look, it's going everywhere, hang on," Camilla says as the ink leaks from the pen and an aide rushes forward to take it from her.

"I can't bear this bloody thing! What they do, every stinking time," Charles adds.

Grieving Charles has had a whirlwind of engagements since his mother, the Queen, died on Thursday, aged 96.

Following his trip to Northern Ireland, King Charles returned to London, and joined other members of the royal family – including Prince Harry and Meghan Markle - as they united in grief around Queen Elizabeth’s coffin at Buckingham Palace.

Prince Harry and his wife are said to have received the casket at the British monarch’s home of 70 years in a small, private gathering, and it’s understood no images will be released of the vigil.

Along with King Charles and his wife, the Queen Consort Camilla, the Prince and Princess of Wales and Prince Andrew were all widely reported to have been in attendance.

It’s also said Princess Beatrice and Edo Mapelli Mozzi, Princess Eugenie and Jack Brooksbank, as well as Zara Philips and Mike Tindall, were at the unprecedented gathering.

The family are also understood to have been joined by Princess Anne, who travelled from Edinburgh to London with the Queen’s coffin, as well as Prince Edward, Sir Tim Laurence, Sophie Wessex, Peter Philips, James, Viscount Severn and Lady Louise Windsor.

The Sussexes and Waleses have already reunited to meet mourners and view the sea of floral tributes left for Her Majesty at Windsor Castle, after years of rumoured rifts between the couples.

The coffin will leave Buckingham Palace and crowds will be able to watch the cortege make the journey along the Mall, Horseguard’s Parade and Whitehall, with the procession to include King Charles and members of the royal family.

The coffin – which will travel in a horse-drawn Gun Carriage - will reach Westminster Hall for the four full days of lying in state, and members of the public will be able to pay respect ahead of the Queen’s state funeral on Monday, September 19.

- The Hits, additional reporting by Bang! Showbiz