The son of former Newcastle-upon-Tyne Whig MP Matthew Ridley and Laura née Hawkins, Ridley followed his father into politics, also as a Whig MP.[4] After unsuccessfully contesting South Northumberland in 1852,[5] he was elected for his father's former seat at a by-election in 1856—caused by the resignation of John Blackett due to ill health[6]—and, becoming a Liberal in 1859, held the seat until 1860, when he resigned after being appointed a Copyhold, Inclosure and Tithe Commissioner.[7]