Peter George Grenfell, 2nd Baron St Just

Peter George Grenfell, 2nd Baron St. Just (22 July 1922 – 1984) was an English peer, a member of the House of Lords from 1943 until his death.

Life Grenfell was the only son of Edward Grenfell, a partner in Morgan, Grenfell & Co., director of the Bank of England, and Member of Parliament for the City of London, and his wife Florence Emily Henderson. He was educated at Sandroyd School and Harrow School. In July 1935, while he was still there, his father was raised to the peerage as Baron St Just, of St Just in Penwith in the County of Cornwall.

During the Second World War, Grenfell was commissioned as a Lieutenant into the King's Royal Rifle Corps. On 26 November 1941, his father died and he succeeded as Lord St Just, They lived at Wilbury House in Wiltshire; Maria continued to live there until her death in 1994.

By his first wife, St Just was the father of Laura Claire Grenfell (born 1950), and by Maria Britneva he had two further daughters, Katherine Grenfell (1957), and Natasha Jeannine Mary Grenfell (1959). His daughter Katherine married Oliver Gilmour.