Verena Lafferentz, who has died aged 98, was the last surviving grandchild of the German composer Richard Wagner and the fourth and youngest child of his only son Siegfried and his English-born wife Winifred.

Adolf Hitler had a fanatical admiration for Wagner’s music and, after the secretly bisexual Siegfried’s death in 1930, developed an extremely close relationship with his widow – so close that many believed they were lovers. In 1933 there were rumours that they might marry.

The Führer was reported to be “particularly fond” of Winifred’s four blonde children, Verena and her older siblings Wieland (1917-66), Friedelind (1918-91) and Wolfgang (1919-2010). They called him “Uncle Wolf” and regarded him as a father figure.

Verena Wagner, nicknamed “Nickel” by her family, was born on December 2 1920 and grew up in the Villa Wahnfried, Richard Wagner’s home in Bayreuth. After her father’s death, her mother, owing to her infatuation with Hitler, was allowed to run the Bayreuth Festspielhaus without direct Nazi interference.

Each summer, in the run-up to and during the Second World War, Hitler attended the Bayreuth Festival, and the Villa Wahnfried became his second home.

In contrast to her older sister Friedelind, whose outspoken criticisms of Hitler and the policies of the Nazis led to her leaving Germany in 1939, it seems that Verena, described as “a frequent visitor and vacation guest at [Hitler’s] mountain snuggery”, became so close to the Führer that in 1940, when she was 20, like her mother before her she was mooted as a possible spouse for the then 51-year-old German leader.

Sent during the war to Überlingen on Lake Constance, in 1943 Verena Wagner married Bodo Lafferentz, a high-ranking officer on the staff of the SS’s “Race and Settlement Central Office” whose mission was to insure the organisation’s racial purity.

In 1945, as defeat loomed, she tried to flee across the lake to Switzerland with her husband and her brother Wieland and his wife. But the Swiss authorities refused to let the boat ashore and they were forced to return to Germany.

Despite their close ties to the Nazis, the Wagner family got off lightly during the postwar denazification period. Winifred was forced to pay only a token fine. Her sons, Wieland and Wolfgang, were allowed to restart the Bayreuth Festival.

But the 1960s brought a new reckoning in Germany, with some of the Wagner great-grandchildren raising embarrassing questions about the wartime activities of their parents and grandparents.

Verena, who had no artistic ambitions of her own, remained largely aloof from the internecine feuds and power struggles that followed.

Verena Lafferentz was an honorary member of various international Wagner societies. In 2003 she attended the International Richard Wagner Congress in Copenhagen and was a guest of honour at a performance of Die Walküre by the Royal Danish Opera, with Queen Margrethe, Prince Henrik, the patron of the Wagner Congress, Wolfgang and Gudrun Wagner, and Birgit Nilsson.

Verena Lafferentz’s husband Bodo died in 1975 and she is survived by their three daughters and two sons. Her eldest child Amelie is understood to be the custodian of letters between Winifred Wagner and the Führer spanning more than two decades, which have been kept under lock and key away from the prying eyes of scholars, sparking much prurient speculation about their contents.

Verena Lafferentz, born December 2 1920, died April 19 2019