Hundreds of millions expected to tune in around the world as BBC hopes viewers will camp out in front of the TV

Saturday is set to be the biggest TV day of the year with hundreds of millions expected to tune in around the world to watch Prince Harry marry Meghan Markle and Chelsea take on Manchester United in the FA Cup final.

Overseeing the footage of the wedding ceremony from St George’s chapel in Windsor will be the BBC’s ceremonial events editor, Claire Popplewell, along with Alison Kirkham, controller of factual commissioning, while later in the day football’s oldest domestic cup competition will be overseen by the director of BBC Sport, Barbara Slater.

Months of planning have gone into the coverage since the date of the wedding was announced as the same day as the FA Cup final.

Slater hopes viewers will “camp out in front of the TV for the day”, with the royal wedding taking place at noon and the football kicking off at 5.15pm.

“They dovetail really well in that I think it’s going to be entirely possible to do all of the usual brilliant FA Cup build up but actually what we’re hoping is there’s a massive inheritance. It’s absolutely huge and I think the events will feed off each other.”

Kirkham said the events would “bring the nation together. This day will demonstrate [at a time] when there’s lots of talk about box sets that there are still moments when the nation wants to come together to watch television live and it’s a communal shared experience.”

Facebook Twitter Pinterest Hundreds of international reporters have already descended on Windsor. Photograph: Geoffrey Swaine/Rex/Shutterstock

Reports of how many people watched Prince William’s wedding to Kate Middleton vary – as many as 27 million people are reported to have watched it in the UK. This time, the National Grid is forecasting about 25% less demand for energy than seven years ago because Harry and Meghan’s nuptials are not taking place over a bank holiday.

Hundreds of international reporters have already descended on the town, with hotel rooms going for thousands of pounds, and cafes and even churchyards being bought up by rivals to gain the best camera vantage points. Camera drones can’t be used for security reasons.

Popplewell, who directed coverage of William and Kate’s wedding said “space is so tight” compared with Westminster Abbey but with cameras now smaller than they were seven years ago they could make filming the ceremony “more discrete for the couple”.

The vows will be shot almost entirely by tiny, remote-controlled cameras disguised within the chapel around the altar.

Another key challenge for Popplewell is having to rig Windsor Castle with the Queen and royal family in residence. “The riggers are just as important as the director, they can make or break those relationships – how they lay their cables, are they discrete etc,” she said.

Trust is key. Kirkham’s work on the documentary about Princess Diana and her sons helped the BBC secure the engagement interview with Prince Harry and Megan, for example.

She said there had been respect towards the palace’s privacy but that they “respect our editorial integrity as well”, and she said the tone would be “inclusive and modern”.

Claire Enders, founder of internet research company Enders Analysis, thinks more young people will watch the wedding, or share images of it, on their mobile, while her colleague Gill Hind said: “There will probably be higher audiences in the US than last time but probably less interest elsewhere.”

Coverage of the FA Cup final will help, though, and there will be links during the day made between the presenters of the wedding coverage and the team at Wembley, fronted by Gary Lineker, Gabby Logan and Alan Hansen.

Slater said: “These are really treasured and cherished events. And the responsibility to make sure you’re covering them in the best possible way is huge. We are trying to give that audience at home the best seat in the house at the wedding or at the football match.”

ITV has similar hopes, said Julie Etchingham, who is co-presenting with Phillip Schofield once again, and whose research has ranged from royal history to watching Markle’s drama Suits.

“There will also be differences too because of the US angle. We’ve got exclusive access to Sentebale, Prince Harry’s charity in Lesotho. So there will be a sense of them as a couple and from around the world.”

Like the BBC, Etchingham and Schofield’s aim is to “capture the spirit of the day … it is a time of celebration and when people and the nation breathe out.”