A State Memorial in Wellington to mark the death of Queen Elizabeth II, the longest reigning monarch in British history, has begun.

The service is being held during a national day of mourning and began at 2pm in Wellington Cathedral of St Paul.

Prime Minister Jacinda Ardern has brought her family with her to remember the Queen.

Neve was spotted sitting on Clarke Gayford's lap, with the pair following along using an official programme. They are sitting a number of rows behind Ardern.

Organ music could be heard as mourners awaited the procession from outside.

A mihi whakatau rung through the cathedral and ahead of the processional cross and lights, a karanga was called.

A slow processional led by rev Tim Handley moved slowly down the aisle towards the altar. A large cross and candles werecarried at the front of a long line of reverends and dignitaries.

An organ rendition of God Save the Queen played softly through the cathedral before the Parade of the Queens Personal flag for NZ began.

The flag was draped with mourning ribbons and was carried up the aisle by captain Joel Ebbing RNZALR before being received at the high altar by the Acting Dean.

The flag reached the high altar and was placed by the acting dean alongside the cross and lights. Ebbing stood and saluted the flag.

Prime Minister Jacinda Ardern and Governor-General Dame Cindy Kiro walking past a plaque for Queen Elizabeth II, as they arrived at New Zealand's State Memorial. Photo / Aaron Dahmen

A national minute of silence was held before Reverend Katie Lawrence welcomed Dame Cindy Kiro, Jacinda Ardern, the speaker and others to the service with an opening prayer.

Lawrence gave an overview of the Queen's 70 years of service, and her strong personal faith.

"The queen visited Aotearoa nz ten times first in 1953, during which she laid this cathedrals foundation stone, and finally during her golden jubilee in 2002," she said.

"As we mark the queens death here today and give thanks for her extraordinary life may we look to a positive hope filled future."

The Right Reverend Justin Duckworth then stood to deliver a karakia before the cathedral stood for the national anthem led by the choir.

The sentences were read in both English and te reo Māori by Lawrence and Duckworth.

A hymn was sung by the choir, accompanied by those present in the cathedral.

Prime Minister Jacinda Ardern arriving with Clarke Gayford and Neve. Photo / Mark Mitchell

Visible from the mezzanine were the open booklets of mourners as they sung along.

The venerable Don Rangi, bishop Waitohiariki Quayle, and cardinal John Dew stood at the front of the cathedral as youth representatives lit candles in remembrance.

Silence was kept as the candles were lit alongside a portrait of the Queen and the sovereign collar.

Don Rangi then read a prayer of remembrance followed by Bishop Quayle.

The armeds services Parade of the Queen's Colours during the Queen's State Memorial Service at Wellington Cathedral of St Paul. Photo / Mark Mitchell

Cardinal Dew was last to read the prayers and act of remembrance as the choir prepared to sing the Lords Prayer.

Prime Minister Jacinda Ardern has taken to the front of the cathedral for a historical reading - an excerpt of "the royal visit to New Zealand" which details the Queen and Duke of Edinburgh's departure from Bluff at the end of their first visit to Aotearoa.

Voices New Zealand have stepped out from the choir towards the front of the cathedral to sing Hine e Hine. It's a slow, haunting melody which is ringing through the rows of people sitting quietly

members of the public watching the Queen's State Memorial Service on the screens on Parliament Grounds in Wellington. Photo / Mark Mitchell

St Mary's college head girl Erana Ngarimu is delivering a Gospel reading of John 10:11-16. She is dressed in her school uniform and stands in the pulpit to the right of the aisle.

A hymn which was sung at the wedding of Princess Elizabeth and Philip Mountbatten is now being sung by all in the cathedral.

Dame Cindy Kiro is taking her place in the pulpit to the left of the aisle in preparation for her tribute.

She said New Zealand saw a queen who would keep us in her heart and prayers and stay by us in times of sorrow.

"With each of her ten visits to New Zealand, the Queen left another indelible mark and came to know and love our country.

"I am honoured to have served as 16th governor-general to the Queen," she said.

One of the final photos of the Queen shows her standing in a room in Balmoral, smiling as she waited for the new Prime Minister of the UK.

"I am sure the Queen's undying spark came from the pleasure she took in her work which she carried out with unwavering care until the end of her life

"She supported over 600 charities whose work helped the sick and lonely, and whose work helped protect the natural world.

"She served all the peoples of the commonwealth to whom she pledged her life. In fulfilling those duties she honoured her father who she loved so dearly and lost so young.

"Our Queen gave us a lifetime of dedicated service. She demonstrated our ideals values and beliefs matter deeply."

Members of the public watching the Queen's State Memorial Service on the screens on Parliament Grounds in Wellington. Photo / Mark Mitchell

Governor-General Dame Cindy Kiro will also speak at the service, and reflect on the late Queen's life of service and her relationship with the country.

There will be a reading from St Mary's College head girl Erana Ngarimu and a pictorial montage of the late Queen accompanied by the Choir of Wellington Cathedral of St Paul.

Then, the national anthem God Save the King will be sung by all before the Queen's Colours and Personal Flag for New Zealand are marched out of the Cathedral.

The service is closed to the public but will be screened outside Parliament at a free, family-friendly event.

While Wellington is holding the national memorial there are other services going on around the country including in Auckland and in Christchurch.