(AFP) - Final preparations were under way on Friday as anticipation reached fever pitch for the wedding of Prince Harry and Meghan Markle, ahead of the mother-of-the-bride's meeting with Queen Elizabeth II.

Doria Ragland is expected to meet the Queen for afternoon tea at Windsor Castle, where the ceremony will take place, with speculation still rife over who will walk the bride down the aisle after it was confirmed her father Thomas Markle would not attend.

Preparations for the showpiece event were shaken on Thursday when Markle confirmed that her father would not travel from his Mexico home after undergoing heart surgery following a paparazzi scandal.

Despite the pre-ceremony fiasco, Meghan was smiling as she was snapped arriving for Thursday's dress rehearsal, which also saw military marches and a dry-run of the carriage procession that will whisk the couple around Windsor to greet the crowds after their wedding at St George's Chapel, in the castle grounds.

The couple made a brief appearance, surprising crowds milling around the rehearsal route by pulling in to Windsor Castle via the famous Long Walk promenade.

Meanwhile, Violet Bakery in east London was on Friday putting finishing touches on the "ethereal" lemon and elderflower wedding cake, which it said would be displayed in a special "installation", according to Harry's Kensington Palace office.

Ingredients for the cake, which will be assembled at Windsor on Saturday, include 200 Amalfi lemons, 500 eggs and 10 bottles of elderflower cordial.

Markle's mother met with Prince Charles and his wife Camilla on Thursday, and will accompany her daughter and future son-in-law when they meet the Queen later on Friday.

Ragland has been suggested as a replacement for Thomas Markle in walking the bride down the aisle, as has Markle's close friend Markus Anderson.

Details about Markle's wedding dress remain a closely-guarded secret, and will not be revealed until the bride arrives for the service.

Mother and daughter will spend Friday night together at the Cliveden House Hotel, a 30-minute car ride from Windsor Castle, while Harry will stay with his brother Prince William at the nearby Coworth Park hotel.

- 'Sorry for her' -

Security forces have transformed the picturesque town into an impregnable fortress.

Every nook and cranny has been scoured and every imaginable security measure deployed to guarantee the safety of the royal couple and the tens of thousands of spectators set to flood the streets.

Diehard royalists have already started camping out in the town to secure the best viewing spots along the carriage route.

But among the tourists milling around the historic town ahead of the big day, there was sympathy for Markle over the last-minute crisis with her family.

"I do feel a bit sorry for her. It's all so complicated, isn't it? Families are always complicated," said Annie Warwick, a tourist visiting Windsor with her daughter, Katie.

Much of the week has been overshadowed by speculation about whether or not her father would attend.

He was originally reported to have pulled out after allegedly posing for a set of staged photos which sold for a reported £100,000 ($135,000/114,000 euros) -- in a breach of royal etiquette.

US celebrity news website TMZ cited sources as saying he had agreed to the photographs in a bid to improve his image.

"He was trying to explain his side of things, that him working with the paparazzi for those staged photos was an attempt to recast his image to show him as a loving father who was getting ready for his daughter's wedding, and not as a reclusive lush," reporter Sean Mandell told the BBC.

The attendance of Harry's grandfather Prince Philip is also in doubt as he recovers from hip surgery.

Despite the rocky build-up, at least Britain's unpredictable weather looks set to behave, with a forecast for clear skies and mild temperatures.

© Agence France-Presse