The Prince of Wales joined senior politicians at the ceremony paying tribute to the lives of the former Labour leader and his wife Audrey.
He died at his home in East Sussex in March just before his 93rd birthday and 11 days after his wife's death.
Lord Callaghan of Cardiff, nicknamed Sunny Jim, was unique in occupying the four offices of state; Chancellor, Home Secretary, Foreign Secretary and Prime Minister. He was in Downing Street for three years before being defeated by Margaret Thatcher in 1979.
In his address, Lord Healey, the former chancellor, described Lord Callaghan as "the greatest prime minister since Clem Attlee". He said: "Jim was a great man with a great wife and theirs was a great marriage for which we should all be grateful."
Baroness Williams of Crosby, former leader of the Liberal Democrats in the Lords, recalled that when Lord Callaghan was asked whether he was New Labour or Old Labour, he responded: "Original Labour".
She spoke of his common touch and said he had always maintained his personal authority, "openness and modesty". Baroness Williams said Labour lost the 1979 general election not because of him but in spite of him.Reuse content