Queen Elizabeth II has been described as a “gracious, warm and friendly” sitter by the latest artist to paint an official portrait of the monarch.

Award-winning painter Isobel Peachey, 31 – believed to be the youngest woman commissioned to paint the monarch – praised her subject as she unveiled the new work.

Ms Peachey was asked by Cunard to create the picture, which will be hung in its new cruise liner Queen Elizabeth, and revealed how she and the sovereign had passed the time by talking about the changing of the guard during the sittings at Buckingham Palace.

Speaking at the unveiling at the National Portrait Gallery, the artist said: “What can I say about the commission? It was wonderful.

“She’s sat for so many artists in the past, it isn’t anything new for the Queen but she was gracious, warm and friendly and wonderful to have as a portrait sitter.”

The artwork is a three-quarter-length painting and shows the sovereign sitting in an ornate chair in the yellow drawing room at Buckingham Palace. The Queen is dressed in blue and wearing Queen Victoria’s collet necklace and earrings.

Three sittings with the monarch were held at her official London residence over three consecutive months from October last year to make preparatory sketches, and the painting was created between March and July.

The artist added: “We talked, the Queen wanted to know about the commission and wanted to know a little bit about me and my career.

“Each sitting took place as the changing of the guard was taking place, so we had that and the music that accompanied it to talk about.”

Last year Ms Peachey was named the winner of the BP Portrait Award’s travel category and received £5,000 to visit Belgium and Switzerland to sketch and paint portraits of enthusiasts taking part in historical re-enactments.