William III inherited estates at Glantonbury Manor and at Barrington Court from his father in his native county of Somerset.
His three marriages were to Elizabeth Rivett (1656), Margaret Osborne (1675) and, thirdly, to Jane Ellys.
In 1680, and subsequently, he supported the rebellion of his friend James Scott, 1st Duke of Monmouth (1649–1685), entertaining the pretender to the throne several times at Barrington and providing him with horses and money.
As was the case with many of his wealthy relatives—such as his brother Edward (1629–1703) of Downside near Shepton Mallet—this was possible only by dint of massive payments of gold coin to King James II.
There is no evidence that anyone on the William Strode III estates was executed, but remains of many dead (because less affluent) Somerset rebels were displayed at this time of the "Bloody Assizes".