You could compress it a bit, but the standard is to write the postcode and the country name on lines of their own, and usually the post town too (that's "Sutton Coldfield" here). So trying to compress down to five lines would require really weird formatting (and possibly confuse the automatic postcode-reading hardware).

(http://www.royalmail.com/personal/help-and-support/How-do-I-... specifically wants postcode on a line of its own.)