William Beardsley and his wife Mary Harvey were natives of England and were married there. They were members of the church of the Reverend Adam Blackman. Together with his 4 children they emigrated to New England in 1635, aboard the good ship Planter.

Dec. 7, 1636, he took oath of office and was made a 'freeman'. The family resided briefly in Massachusetts Bay Colony, before removing to the Pequonock Plantation of Connecticut.

They became the founders of Stratford, Connecticut in 1639. William is thought to have originally come from Stratford-on-Avon in England and may have been responsible for naming the town Stratford, Connecticut. He was deputy to the General Court at Hartford for eight terms from 1645 to 1658. Throughout his life he was active in judicial matters in the colony.