His grandfather Thomas Scawen and great-uncle William Scawen were wealthy merchants in London and acquired large estates in Surrey including Carshalton Park which his father inherited.
I came an independent man into this House” Scawen attended the Surrey county meeting of October 1774, without intending to be a candidate; but was persuaded to stand for Surrey in the 1774 general election with the support of the leading interests in the county, in order to keep out Sir Joseph Mawbey.
Scawen did not stand again for Surrey in 1780, and appears to have made no other attempt to re-enter Parliament.
[1] The Scawens developed Carshalton Park in the 18th century including an early grotto and canals that fed mills nearby.
[2] There were apparently financial difficulties and Scawen began to sell some of his Surrey property in 1774, shortly after succeeding his father, and during the next few years mortgaged or sold more of it, until in 1781 his remaining estates were disposed of by the trustees in whom they were finally vested.