Article continues below advertisementMick Jagger's family is in shock and desperate for answers after his granddaughter Assisi Jackson's longtime partner, Alexander Key, went missing in the U.K.The 37-year-old chef - who shares two children with Jackson, 33 - was last seen on Friday, January 23, in the afternoon at the Cobweb Inn, a pub in Boscastle.Article continues below advertisementMissing Person AlertSource: @devonandcornwallpolice/FacebookMick Jagger's granddaughter's partner, Alexander Key, has gone missing in Cornwall.CCTV footage shows Key sitting alone at the bar around 2:30 p.m.