Find the last name of the first ever contact person of the organization with the highest UK Vat number.
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.uk_vat_number = (select max(uk_vat_number) from organizations) order by t2.date_contact_to asc limit 1