Jeger was elected to the St. Pancras Borough Council (1945–59) and the London County Council (1952–55), on which she represented Holborn and St Pancras South. Her husband died in 1953 and she was selected as Labour's candidate in the resultant by-election in Holborn and St Pancras South. She won the by-election, held on her birthday, by 1,976 votes, slightly increasing the Labour majority. She just retained her seat at the 1955 general election by 931 votes, but lost the seat to the Conservatives in the 1959 general election by 656 votes, losing to Geoffrey Johnson Smith.