Sister Agnes Walsh, who sheltered a family in her convent in France, was among 25 recipients honoured posthumously with the award, the creation of which was announced last year by Prime Minister Gordon Brown on a visit to the Nazi concentration camp at Auschwitz.

Two surviving recipients, Sir Nicholas Winton and Denis Avey, were given their medals in person in Downing Street.

Mr Brown said all were "true British heroes and a source of national pride for all of us" and should inspire future generations.

Sir Nicholas Winton, who is now 100, organised the rescue of 669 mainly Jewish children by train from Prague in 1939.

Mr Avey, 91, exchanged places with a Jewish inmate at Auschwitz while he was a prisoner of war – gathering facts about conditions and helping an inmate survive by sharing supplies.

The solid silver medallion bears the inscription "in the service of humanity" and, on the reverse, "in recognition of xxxx whose selfless actions preserved life in the face of persecution".

It was announced after a long campaign by the Holocaust Education Trust – backed by MPs – for the Holocaust heroes to be awarded MBEs and OBEs posthumously.

Mr Brown said: "These individuals are true British heroes and a source of national pride for all of us. They were shining beacons of hope in the midst of terrible evil."

Welcoming the presentations, Karen Pollock, chief executive of the Holocaust Educational Trust, said: "We are delighted that our initiative received widespread support and that the British Government has given these brave people the recognition they have long deserved.

"They provide a template of courage for today's young people - and clearly highlight the difference that can be made by standing up against injustice, hatred and prejudice.

"Many of these extraordinary British men and women risked their lives and never spoke about afterwards.

"They are true unsung heroes."