Find the last name of the latest contact individual of the organization "Labour Party".
select t3.individual_last_name from organizations as t1 join organization_contact_individuals as t2 on t1.organization_id = t2.organization_id join individuals as t3 on t2.individual_id = t3.individual_id where t1.organization_name = "Labour Party" order by t2.date_contact_to desc limit 1