The frontrunner in the Labour leadership race has been accused of telling “tall tales” about her working-class back story growing up under Margaret Thatcher and watching her father worry about layoffs at the local docks.

Rebecca Long Bailey, the shadow business secretary, also faces doubts about her status as favourite to succeed Jeremy Corbyn, after private union polling of party members showed that she is behind rivals Sir Keir Starmer and Emily Thornberry.

The Corbyn ally has repeatedly told interviewers her outlook as a politician was shaped by watching her father worry about losing his job at Salford docks. On election leaflets, she declared: “They say your experiences shape who you are and mine certainly have. My dad, Jimmy, worked on the Salford docks and