Crowds gather ahead of Duke of Westminster's society wedding of the year to Olivia Henson with Prince William as usher and 400 guests - as local people are treated to free ice cream and 100,000 flowers

Crowds have formed outside Chester Cathedral ahead of the Duke of Westminster's society wedding of the year to Olivia Henson.  

Hugh Grosvenor, 33, will wed Olivia, 31, at the cathedral in Cheshire today, with guests jetting in from around the world. 

The 7th Duke, the richest man in Britain under forty - worth £10.42billion - is godfather to Prince Williams's son Prince George and Prince Harry's son Archie.

William will be an usher at the service among 400 or so expected guests - while Prince Harry will not be in attendance. 

The Princess of Wales, who has been out the spotlight as she undergoes preventative chemotherapy, is not expected to attend. 

Photos from this morning show excited fans forming a crowd outside the cathedral ahead of the Church of England ceremony starting at midday. 

The Duke will pay for free ice cream, gelato and sorbet for Cheshire locals from three local independent cafes so they can join in the celebration. 

Meanwhile, a staggering 100,000 flowers have been planted throughout the city - all paid for by the Duke - which will be donated to charity following the ceremony. 

This week a floral arch was constructed around the huge West Door of the 1,000-year-old Cathedral in the heart of the city. 

On a road into the city near the entrance to the Grosvenor Hospital, staff dressed a pair of mannequins in suit and wedding dress with photos of Hugh and Olivia's faces attached. 

Given the presence of the heir to the throne at the event, security precautions have also been in evidence, with detectives seen chatting with local Cheshire Police officers outside the Cathedral this week. 

Police sniffer dogs were seen checking drains around the precincts of the building for any traces of explosives.

Eaton Hall, a mock French chateau set in 10,872 acres of Cheshire (50 acres of which is elaborate formal gardens) is where the couple intend to live after they are married, and is the perfect place for a party. 

Cheshire Farm Ice Cream, based in the heart of Chester Market, will be offering a range of Cheshire Farm single-scoop ice-creams or slices of a new lemon-sponge flavoured arctic roll.

The lemon-flavoured arctic roll has been specially created in acknowledgement of The Duke and Olivia's lemon-flavoured wedding cake that guests will be served at the wedding reception.

Ed Warrington, owner of Cheshire Farm Ice Cream outlets, said: 'As a local business we're delighted to be part of The Duke and Olivia's initiative to provide free ice cream to the public in celebration of their wedding.

'All at Cheshire Farm Ice Cream wish them the very best for their wedding day.'

The couple have been scrupulous about not giving away details of the reception and 'we have also been asked not to do any social media posting when we get there', said a guest.

It is likely to be a green event as both Hugh and Olivia are eco minded, and it is understood that flowers used at the ceremony and reception will be pressed and made into sustainable artworks afterwards, rather than simply being thrown away.

Olivia, who went to Marlborough College, like the Princess of Wales and Princess Eugenie, is senior account manager at Belazu, an environmentally friendly company which imports chef-quality, sustainably-sourced ingredients.

Hugh has increasingly started to initiate various eco-friendly practices, including renewable energy projects, green building codes and biodiversity conservation efforts.