Thomas Aldam was born at Warmsworth near Doncaster, Yorkshire in about 1616.  His mother was Margaret Lord, and she had a brother Thomas Lord. His father's first name, William, is given in the 1619 baptism record of his sister Margaret.
Thomas was at first a Puritan, and then a separatist (one who distanced himself from the Church of England). He became a Quaker in 1651, together with his mother, wife and two sisters, after hearing George Fox preach.
In 1652 he was imprisoned after opposing Thomas Rookby, the minister at Warmsworth. He was also fined £93 for refusing to remove his hat before social superiors and refusing to pay church taxes. He was held at York Castle, where he wrote many letters and from where he sought to establish links between Quakers of the North of England and printers in London. He also wrote a number of religious papers during this time. He was released after some two and a half years.
In 1654, 1655 and 1658 he suffered physical attacks for his Quaker beliefs.
At one stage he was given an audience with Oliver Cromwell, and, in a symbolic act, tore his hat into pieces as an illustration of his belief that Cromwell would soon be removed from his position. Of Charles II, he is alleged to have said, "I find nothing to this Man".
In the later 1650s he promoted a general Quaker fund for missionary work. He also visited other Quakers in prison, and sought to draw attention to their suffering.
Thomas is included among the Valiant Sixty, a set of very early Quakers who were active in promoting Quakerism.
Thomas Aldam died in June 1660, probably at Warmsworth, leaving a sizeable estate. His wife died three months later. He was buried at the Quaker burial ground at Warmsworth on 14 June 1660.