Prince Harry and Meghan Markle's big day in May 2018 is set to be the wedding of the year, with nothing but the best services being provided to celebrate the monarchy's very modern romance.

IBTimes UK revealed the predicted cost of the royal wedding over the weekend. Founder of wedding planning website and app Bridebook, Hamish Shepard, cited it would set the Royal family back a cool £1.5m.

He said: ''Meghan and Harry's wedding is expected to cost £1,463,273 [$1,964,312], and that's not including the honeymoon or the £10m expected security costs involved on top. Their wedding will cost almost 100 times the average cost of a wedding.

''Their highest expenditures are likely to be the catering, drinks and the decor.''

But it's not just the venue – St George's Chapel at Windsor Castle – or the dress that will rack up the wedding bill.

Harry and Markle's wedding cake is also thought to come at an eye-watering price many times more expensive than the national average.

While most couples will go for a cake costing anywhere between £95-900 depending on the baker and number of tiers, the royal wedding cake is on another level of indulgence.

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Prince Harry and Meghan Markle receive flowers on their walkabout Getty

Shepard explained: ''A stunningly-decorated cake from a top cake maker will start from £4,000 and need to be at least 8 tiers to give a slice to each of the guests.''

He has also predicted who is in the running to create the cake, adding: ''London-based Fiona Cairns, the royal baker behind the Duke and Duchess of Cambridge's wedding, or the society favourite Rosamund Miller are likely to be top contenders.''

Former royal chef Darren McGrady also delivered his thoughts on what Harry and Markle will decide in terms of their wedding cake, citing that they could break tradition by opting for an American classic to pay homage to the actress' roots.

He told Entertainment Tonight: "This could be the very first time where they break with tradition and don't have a traditional fruitcake.

"It wouldn't surprise me if Meghan chose a traditional American cake – a layered sponge cake – and found an American baker in London to make it," he added, revealing that the bride traditionally chooses the wedding cake flavour.

If Markle opts for a US-style cake, Chef Damian Wawrzyniak told IBTimes UK that "chocolate would work pretty well for American style wedding cake", which so happens to be Prince William's favourite flavour. Wins all round.