#! perl -sw
use strict;

#         1         2         3         4         5         6         7         8
#234567890123456789012345678901234567890123456789012345678901234567890123456789012345
sub by_priority{my$r=qr/^(?:Service|Organisation|FAQ)/;$a cmp$b|($a=~$r&-1)+($b=~$r)}

my @stuff = qw/
the
Services_s
FAQ_A
quick
FAQ_C
Organisation_3
brown
FAQ_B
fox
Services_p
jumps
Services_q
over
Organisation_1
the
lazy
Organisation_2
dog
/;

print $_,$/ for sort by_priority @stuff;
__END__
c:\test>test
FAQ_A
FAQ_B
FAQ_C
Organisation_1
Organisation_2
Organisation_3
Services_p
Services_q
Services_s
brown
dog
fox
jumps
lazy
over
quick
the
the

c:\test>