In 1738 he was appointed to command HMS Hampton Court, and was senior officer at this station until the arrival of Admiral Edward Vernon in the following year.

His opportunity arrived in 1739, when, during the War of Jenkins' Ear, he served under Vernon in the attack on Portobello, in the isthmus of Darien.

He led the squadron into Boca Chica, placing his vessel, the Hampton Court, alongside the strongest part of the fortifications.

In 1741 Brown was appointed to the office of commissioner of the navy at Chatham, a situation which he held with unblemished reputation until his death, on 23 March 1753.

There was a portrait of Brown in the Painted Hall at Greenwich, which subsequently passed in the hands of the successor institution, the National Maritime Museum.