A rehearsal for the royal wedding is due to take place in Windsor later.
Some 250 members of the armed forces are expected to take part in Saturday’s festivities, lining the streets as the newlywed Prince Harry and Meghan Markle head on a 25-minute carriage ride through the town.
After months of planning, Thursday’s dry-run will give organisers a chance to put some finishing touches to the global event.
But as the big day nears, it was reported that Ms Markle’s father has been left “heartbroken” as he will miss the wedding.
Thomas Markle is said to have successfully undergone heart surgery on Wednesday to implant three stents, so will be unable to give his daughter away as he needs time to recover.
He told US website TMZ he was “OK”, although it will take a “long time to heal”.
“Staying in the hospital a few more days. Not allowed to get excited,” he said.
Ms Markle’s mother, Doria Ragland, has been tipped as a stand-in to walk their daughter down the aisle at Windsor Castle’s St George’s Chapel.
On Wednesday, Thomas Markle Jr, the brother of Ms Markle, visited Windsor to see where his sibling will marry Prince Harry.
He told the Mirror: “My dad will be heartbroken that he cannot be with Meg in Windsor to walk her down the aisle.
“He would have moved heaven and earth to be there.”
Mr Markle Jr said his sister will be a “perfect modern princess” and “one of the best things ever to have happened to the royal family”.
Members of Ms Markle’s family have travelled to the UK amid intense attention from the world’s media.
Meanwhile on Wednesday, her half-sister, Samantha Markle, was reportedly injured following a “paparazzi confrontation” in Florida.
Her partner, named by TMZ as Mark, told the website that their car hit a concrete barrier after attempting to avoid a photographer.
Ms Markle had apparently been left with a broken ankle and a fractured knee and was receiving treatment in hospital, he said.
Mr Markle Jr reportedly said Kensington Palace should have offered his father more guidance about how to handle the intense media spotlight.
Pictures of Mr Markle Sr appeared in a number of British newspapers, which it later emerged were staged, prompting him to drop out of the wedding, telling TMZ he did not want to “embarrass the royal family or his daughter”.
On Monday, he reportedly missed a call from his daughter and she later told him she loved him in a text message and said she was concerned about his health.
Mr Markle Sr changed his mind and said he wanted to be “part of history” and would travel to the UK, but the surgery meant he was prevented from travelling.
Samantha Markle told The Sun she was worried about her father and claimed she had wired money to the 73-year-old.
She said: “He is badly in need of help. I’m dreadfully worried about him.
“He’s completely on his own.”
Despite her parents divorcing when she was six, Harry’s future wife has remained close to her father.
Responding to reports surrounding her father’s attendance at the wedding, Kensington Palace said on Monday that it was a “deeply personal moment for Ms Markle.”