Baroness Worthington, who worked briefly for Scottish and Southern Energy, insisted executives running the electricity and gas giants were not “sharks” who drove around in expensive cars.
However, her staunch defence of the industry contradicted the sustained criticism of energy price rises that her party leader has mounted in recent months.
In one of his first concrete policies announced as he opened the Labour conference, Mr Miliband declared he would change the law to force gas and electricity companies to pass on price cuts to customers.
He has attacked energy firms for “ripping off” customers after a series of steep price rises.
However, in an interview with the House magazine, a parliamentary journal, Lady Worthington, Labour’s energy spokesman in the Lords, said companies “do a really difficult job very well”.
“Having seen from within, they keep the country running... very, very professionally,” she said. “And they’re not out there running around in Jaguars. They’re not sharks.”