Thirty years since skateboarding teen Marty McFly first went time-travelling, Lea ‘Lorraine’ Thompson and Christopher ‘Doc’ Lloyd celebrate a remarkable trilogyLea Thompson smiles. “You can kill and kill and rape and maim and plunder,” she says sweetly. “But at some point you have to settle down and say: ‘Where’s the sewer?’”Thompson, who played Marty McFly’s mother Lorraine in the Back to the Future trilogy, is sitting next to a plate of Back to the Future cupcakes.