#!/usr/bin/perl -w
use strict;
use Data::Dumper;

my $currec = undef;
my @recs =();

while (<DATA>)
{
    if ( /^Record\s+(\d+)/)
    {
        $currec = $1
    }
    elsif ( /^
            (\S+)   # non spaces. This is the key name
            \s+     # some spaces follows
            :       # and a colon
            \s+     # more spaces
            [^\[]+  # any non bracket character
            \[      # an opening bracket
            (
            [^\]]*  # any more characters before a closing bracket
            )
            \]      # a closing bracket
            /x)
    {
        $recs[$currec]{$1} = $2;
    }
}

print Data::Dumper->Dump([ \@recs ], ['original']);

my @twelves = grep { $recs[$_]->{Ref} == 12 } 0.. $#recs;

print Data::Dumper->Dump( [ \@{[ @recs[@twelves] ]} ], ['twelves']);

__DATA__
=================================================
Record 0

Name                  : John [John]
I/C                   : >123< [123]
Sex                   : 'Male' [Male]
Ref                   : >12< [12]
==================================================
Record 1

Name                  : Pretty [Pretty]
I/C                   : >125< [125]
Location              : 'Female' [Female]
Ref                   : >12< [12]
==================================================
Record 2

Name                  : Kim [Kim]
I/C                   : >124< [124]
Location              : 'Male' [Male]
Ref                   : >11< [11]
==================================================