They listened in silence – some with babes in arms, some in black mourning dress, others in the T-shirts and jeans of daily life – as the voice of King Charles III echoed around St Paul’s Cathedral.

As a service of thanksgiving coincided with the first public address of the new King, it was his words about his “darling mama” that were the focus before anything else at a solemn event which included a lament from a lone Scottish piper and ended with the first singing of God Save the King.

“Most of us have not known life without the Queen,” the congregation of more than 2,000 people – including hundreds of members of the public – was told by the bishop of London, the Rt Revd and Rt Hon Dame Sarah Mullally DBE.

“When she acceded to the throne, the world and the country were both very different places. For seven decades, Her Majesty remained a remarkable constant in the lives of millions: a symbol of unity, strength, forbearance and resilience.”

The Queen had, the bishop reflected, been a nation’s “unerring heartbeat through times of progress, joy and celebration, as well as in much darker and more difficult seasons”.

She said: “All of us are grieving the loss of our head of state, head of the Commonwealth and supreme governor of the Church of England. But the royal family are grieving the loss of a mother, a grandmother, a great-grandmother. How we learn to live with the death of a loved one differs for each of us, but we must all find a way to grieve.”

Those in the pews listened, and sometimes openly wept, to music sung by the St Paul’s Cathedral choir, conducted by Andrew Carwood. It included Behold O God Our Defender by Herbert Howells, Bring Us, O Lord God, at Our Last Awakening by William Harris, and the Nunc dimittis from Evening Service in G by Charles Villiers Stanford.

The hymns were All My Hope on God is Founded, O Thou Who Camest from Above, and The Lord’s My Shepherd, which is said to have been a favourite of the Queen’s. As at her wedding to Prince Philip in 1947, it was to the tune of Crimond by Jessie Irvine.

Earlier, the prime minister, Liz Truss, delivered a Bible reading, Romans 14:7-12. “We do not live to ourselves, and we do not die to ourselves. If we live, we live to the Lord, and if we die, we die to the Lord; so then, whether we live or whether we die, we are the Lord’s,” she read.

Other political figures present included the London mayor, Sadiq Khan, the Labour leader, Sir Keir Starmer, the chancellor, Kwasi Kwarteng, and the foreign secretary, James Cleverly. They listened intently to Truss’s reading before standing for the hymn O Thou Who Camest from Above.

The 2,000 available public seats at the service were allocated on a first come, first served basis. Among those attending was pupil barrister Danielle Carrington, who praised the Queen for her “dignity and grace” as she queued with her mother outside St Paul’s.

The 20-year-old, who had been awarded a scholarship by the Princess Royal, said: “For all generations really, the Queen embodied those ideals of our country, integrity, dignity and grace, and it’s very important from my perspective anyway to pay respect to that.”

Carrington’s mother, Lindsey, said the loss was “like a family grief, a personal grief” rather than that for a monarch, adding: “We knew we could always depend on her [the Queen] in any diplomatic setting.”

Elsewhere among thousands of well-wishers who had formed a line winding from the cathedral round to the tube station streets away, waiting to take their seats, some of those in the crowd spoke of a “personal grief” having felt they had known the Queen without ever having met her.

Karen Wilson, a translator from Surrey, remembered the “real sense of dignity” that came across when she saw the Queen at an engagement in the 1990s. She said the monarch had smiled and waved at her young children as she passed them outside Buckingham Palace on her way from greeting the Emperor of Japan, a moment they will “always remember”.

“I was just moved by the sense of history and occasion. I think I didn’t realise till yesterday how much I loved her,” she recalled.

As darkness fell outside at the end of the service, it was Justin Welby, the archbishop of Canterbury, who delivered the blessing.

“God grant to the living, grace, to the departed, rest, to the church, the King, to the Commonwealth, and all the people, peace and concord, and to all his servants, life everlasting, and the blessing of God Almighty, the Father, the Son and the Holy Spirit, be amongst you and remain with you always.”