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 1, our celebrities settle into the past, hoping they'll achieve their personal goals to turn back the clock - and within the first 24 hours there are already extraordinary changes. Presented by Mariella Frostrup.