What if it were possible to turn back time? Could it be that we all have the power to think ourselves young again? That's the extraordinary claim of an experiment first conducted 30 years ago which the BBC is now re-staging. Six well-loved celebrities in their 70s and 80s - Liz Smith, Lionel Blair, Dickie Bird, Sylvia Syms, Derek Jameson and Kenneth Kendall - have agreed to spend one week living as though it were their heyday - 1975 - to see if re-living your youth can make you young again. Their country retreat has been lovingly restored to be an authentic 1970s home, but it's not just the house that's had a '70s makeover. The celebrities will be wearing the clothes of the 1970s, they'll be cooking the favourite dishes of the time and their pastimes will include 70s TV, 70s video games and favourite LPs from the decade. Overseeing the experiment will be the BBC's man of science, Dr Michael Mosley, and Harvard Professor Ellen Langer, who conducted the original experiment. In Episode 2, each of the celebrity volunteers must come face-to-face with the lives they led in their heyday and take back control of their lives. For Lionel, the most resistant to the experiment, a trip to The London Palladium ends in tears, and for Dickie a trip to Lords Cricket Ground brings the man he used to be back to life. Kenneth is reacquainted with his beloved dogs, and Liz takes up painting again. But just as the experiment seems to be working, a surprise visit from a group of carers shows Michael and Ellen just how far the volunteers still have to go... Presented by Mariella Frostrup.