The lippy fashionistas have built an extremely successful career bullying the famous and not-so-famous into wearing trendy outfits and, appearing on tonight's Friday Night with Jonathan Ross on BBC1, have let slip their deepest and darkest fears.
"I find ageing terrifying," Susannah admitted.
"I don't want to let go for a second… you see so many women who say they feel completely invisible."
She described seeing an image of herself aged 70 as like being "kicked in the stomach".
One thing they will always have, it seems, is each other. Susannah described their relationship as being "like a marriage" while Trinny revealed the surprising extent of their closeness.
"We were so elated at the end of our last series, we snogged," she said.
The sartorial duo have much to be happy about as they survey their career since shooting to fame with BBC2's What Not To Wear. In 2005 ITV successfully poached them, helping them come up with the format for Trinny and Susannah Undress which aired last year.
