He was well known in his own time as a writer on religious controversies, but he is now mainly remembered for his friendship with Jonathan Swift.
The friendship was damaged by Tisdall's wish to marry Esther Johnson, Swift's beloved friend Stella.
Swift's letter was courteous enough in tone - he stressed the practical difficulties of such a marriage since Tisdall was not a rich man, and the Church had not yet found him a salaried position - but he privately expressed his disgust at Tisdall as an "interloper", and their friendship cooled off.
Philip Tisdall, who was later, as Attorney General for Ireland, to be a very powerful figure in the Irish administration, was a cousin of William in the next generation.
Tisdall was well known in his own lifetime for his pamphlets on religious controversies, of which the best known was Conduct of the Dissenters in Ireland (1712).