Crossing’s family can be traced back two generations only. His father Hugh, a Devon merchant, probably hailed from Totnes, though he was living at Dartmouth by 1592. In the following year he became a freeman of Exeter, where he then settled, serving as mayor in 1609 and 1620.
The sudden deaths in 1622 of both Hugh and the Morlaix factor, who were in dispute over the latter’s accounting, landed Crossing with a protracted legal battle with the factor’s executors.
Crossing possessed no known personal ties with Cornwall, and probably relied on his Hakewill connections to secure his election to Parliament in 1626. The principal patron at Mitchell, John Arundell* of Trerice, apparently provided a seat for William Hakewill there during this period, and might therefore have been persuaded to endorse Crossing as well. The same patron may have been at work in 1628, since Arundell’s close relative Sir Richard Carnsew occasionally made nominations to Camelford. Alternatively, Hakewill may have recommended Crossing to his distant kinsman Sir Nicholas Prideaux, who also enjoyed influence at Camelford.
Crossing was appointed to Exeter’s Common Council for life by the 1627 city charter, and became governor of the Exeter French Company in 1631, despite having refused in the previous year to contribute to the Company’s voluntary levy on trade with France. As mayor in 1634-5, he oversaw the smooth collection of Ship Money, and must have been involved in the successful transfer of part of Exeter’s initial assessment to Barnstaple.
