p.s. if you are building a command as Dell suggested (which is the recommended / supported method) then here's an example of using a subquery (using the report above's sql)...this adds in the expression as a subquery.
SELECT `Customer`.`Country`, `Customer`.`Customer Name`,
(Select Distinct count("Customer2"."Customer Name") from "Customer" "Customer2" where "Customer"."Country" = "Customer2"."Country") AS CUSTCOUNT ,
(Select Max ("Customer2"."Customer Name") from "Customer" "Customer2" where "Customer"."Country" = "Customer2"."Country") AS CUSTMAX
FROM `Customer` `Customer`
ORDER BY `Customer`.`Country`
-jamie