Matt and Jenna introduce the Doctor Who Christmas Prequel, The Great Detective, in which Vastra, Jenny and Strax try to persuade the grumpy Doctor to engage again.Matt and Jenna introduce the Doctor Who Christmas Prequel, The Great Detective, in which Vastra, Jenny and Strax try to persuade the grumpy Doctor to engage again.Matt and Jenna introduce the Doctor Who Christmas Prequel, The Great Detective, in which Vastra, Jenny and Strax try to persuade the grumpy Doctor to engage again.