Lord Longford's long career as a champion of the ostracised began early in 1932 when he met and fell under the spell of Eamon de Valera, who was then much reviled in England as he moved to dismantle the Treaty settlement of 1921. Lord Longford, who died on August 3rd aged 95, remained a constant and often lonely champion of nationalist Ireland through many decades when it was without friends or much respect among those who counted in Britain.
Frank Pakenham (as he was known for most of his life) was born in London on December 5th, 1905, the second son of the fifth Earl of Longford, and was educated at Eton and New College Oxford. His elder brother Edward, later the founder of the Gate Theatre and a senator, espoused the Irish nationalist cause at Oxford and was thrown into a pond and had his collection of Gaelic books destroyed after he had spoken at the union in defence of the assassins of Sir Henry Wilson.
As a young man Frank Pakenham steered clear of Ireland and was a rising young Conservative in London at the time of his marriage in 1931 to fellow Oxford graduate Elizabeth Harman, the left-wing daughter of a Harley Street doctor.
In the following year he met Robert Barton, the Wicklow squire who was a signatory to the Anglo-Irish Treaty of 1921 but who had later repudiated it. Utilising Barton's papers and with the benefit of interviews with such survivors as were prepared to co-operate, he produced in 1935 his classic work on the Treaty negotiations, Peace by Ordeal. It showed that partition was not seen as a long-term solution by either side in the Treaty negotiations.
The very fact of presenting de Valera's viewpoint as reasonable was enough to make the book and its author unpopular in Tory England. A few years later he followed his wife into the Labour Party. In 1940, he completed the metamorphosis when he became a Catholic, although in that he had the precedent of his great grand-uncle, Father Paul Mary Pakenham, an ex-grenadier, who converted with Newman, joined the Passionist Order and was the first rector of Mount Argus.
A period of military service at the beginning of the war culminated in a nervous breakdown and he was invalided out. He said it made him realise what it was like to be socially humiliated. But he used his freedom to good effect and was co-author of the Beveridge plan - the blue-print of the post-war British social security system.
He was appointed minister for British-occupied Germany in Clement Attlee's post-war Labour government and created a peer. It was in this context that he first emerged as an exemplar of the Christian message of forgiveness which was to be a recurring theme of his life. At first, few in Britain shared his readiness to forgive the Germans and only the threat of Russia and communism made them see the need to rebuild the German economy. The restoration of the currency which he initiated was the first major step in Germany's post-war economic miracle.
Although proud to be a member of the British government, he counted himself an Irishman, travelled on an Irish passport and supported the Irish rugby team. When, following the ill-managed declaration of the Republic in 1948, the Attlee government copper-fastened partition by the Ireland Act 1949, he voiced his dissent to the Cabinet. He recalled being heard in chilly silence and got no support.
Out of office after the Conservative victory in 1951, he resumed life as a don at Oxford before becoming chairman of the National Bank, a London clearing bank founded by Daniel O'Connell, most of whose branches were in Ireland. A socialist in the City of London was a rare phenomenon in those days. The bank thrived under his leadership. He travelled the length and breadth of Ireland getting to know those who worked for it. He was a friendly, affable man with a good sense of humour who never felt it necessary to pull rank. As a child he had insisted on addressing the servants at home with the prefix Mr.
Frank Pakenham was a go-between with Harold Macmillan in the negotiations with the British government that led to the return of the Lane paintings to Dublin in 1958. In 1960, he floated a proposal that Ireland should rejoin the Commonwealth in return for the end of partition only to find himself repudiated by his old friend, President de Valera.
His brother died in 1961 and he became Earl of Longford. But he passed over the succession to the Irish estate at Castlepollard to his son Thomas Pakenham, the distinguished historian and tree enthusiast, whom he had sent to Belvedere College for a short time.
When Labour returned to power in 1964 he was included in the cabinet by Harold Wilson. But there was little rapport between the two men. Wilson regarded him as a loose cannon with a mental age of 12 and did not heed his advice to intervene more in Northern Ireland. When Frank Longford attended the celebrations for the 50th anniversary of the Easter Rising he was reprimanded at the cabinet.
In 1968, he resigned in protest against the failure of the government to honour its pledge to raise the school-leaving age to 16.
Out of office in 1969, he was the first British politician to advocate the formation of a power-sharing administration in Northern Ireland. Although condemning violence he was convinced the re-unification of Ireland was the only long-term solution.
In collaboration with Prof Tom O'Neill he wrote the official biography of Eamon de Valera, whom he confessed to regarding as a father-figure and whom he was fond of saying was one of the world's great statesmen. The book, published in 1970, was perhaps closer to autobiography than biography.
Released from the cares of office, he embarked on a life devoted to popular writing and to unpopular causes and people. The British press lampooned him as Lord Porn when he headed an inquiry into pornography that included visits to the red-light districts of Copenhagen. His patrician but rather unkempt appearance, his don-like eccentricity, his unworldliness and love of the limelight made him an easy target for ridicule.
He was also reviled for advocating the release of the Moors murderess Myra Hindley. She was only one of many prisoners whom he befriended over the years. Many of these were Irish and included the Birmingham Six, the Guildford Four and the Maguire Seven, whose cause he championed. He lived out to the full the conviction that one must not hate the sinner because one hates the sin. Even those who were critical of his occasional na∩vety and misjudgment could not but acknowledge in him an inspiring and selfless idealism.
He continued to speak in the House of Lords from the Labour benches until a few weeks before his death.
He is survived by his wife Elizabeth, the distinguished biographer, and by seven of their eight children. His eldest son Thomas succeeds him as Earl of Longford.
Peter Stanford Francis (Frank) Aungier Pakenham, Seventh Earl of Longford: born 1905; died, August 2001