Lily Ebert, who is 98, showed the Prince the number tattoo forced on her in Auschwitz, and a pendant given to her by her late mother which she managed to keep by hiding it in her shoe and – when that heel wore out – a daily ration of bread.

She told the Prince: “Meeting you, it is for everyone who lost their lives.”

The Prince, who appeared emotional, leant forwards to clasp her shoulder and insist: “But it is a greater privilege for me.”

Mrs Ebert also met the Duchess of Cornwall, who thanked her for taking part in the event.

“It’s an absolutely lovely portrait,” said the Duchess. “And what’s wonderful is that it is here forever [in the Royal Collection].”

The project, which was personally devised by the Prince, also captures survivors Helen Aronson, Manfred Goldberg, Arek Hersh, Anita Lasker-Wallfisch, Rachel Levy and Zigi Shipper.

Their portraits were created over the course of a year, via the Prince’s Drawing School, by artists Paul Benney, Ishbel Myerscough, Clara Drummond, Massimiliano Pironti, Peter Kuhfeld, Stuart Pearson Wright and Jenny Saville.

Mr Shipper, 92, spent the early part of the war in a ghetto doing slave labour, before being sent on a cattle truck to Auschwitz in 1944.