I had more or less arrived at the script you propose, which does indeed push the calendars into the container table. The problem is that the line

 
$cal->item( 15, 16, 17 )->wrap_content( font({ size => 4, color => 're
+d' }) );
[download]

My challenge is to associate each @days with its corresponding $new_c

The code below I hope shows a bit more clearly what I'm trying to achieve - tho' it doesn't work - perhaps you wouldn't mind taking a look and giving me your comments. (I've done very little with hashes so far so I'm guessing a little bit on how this might be achieved).

#!/usr/bin/perl -w
use strict;

use CGI qw(:standard);
use Date::Calc  qw(:all);
use CGI::Carp qw(fatalsToBrowser warningsToBrowser);
use lib '/home/users/t/my_site.com-90978/lib';

use HTML::AsSubs;
use HTML::Element;
use HTML::CalendarMonth;

# @dates has already been sorted
my @dates = ( 730000, 731158, 731159, 731160, 731161, 731178, 735000 )
+;
my @cals;

print header(), start_html(-title => "Calendars");

# As long as there is a date left in @dates
while (defined $dates[0]) {
  # get the first value from @dates leaving @dates alone
  my $days = $dates[0];
  # find out the year, month and day so we can create a calendar
  my ($year, $month, $day) = Add_Delta_Days(1,1,1, $days - 1);
  # run the CreateCal subroutine with the year and month from the firs
+t date
  # store the returned value in @dates so it can be used the next time
+ through the while loop
  @dates = CreateCal($year, $month, @dates);
}

exit(0);

sub CreateCal {
  # Get the year and month for the calendar
  # as well as the @dates to use
  my ($cyear, $cmonth, @dates) = @_;
  # set up some variables that are local to this subroutine
  my (@days, @temp);
  my %calendar;
  my $new_c;
  my $t;
  # Process each $days in @dates
  foreach my $days (@dates) {
    # Get the year, month and day of $days
    my ($year, $month, $day) = Add_Delta_Days(1,1,1, $days - 1);
    # does it match the calendar we are creating?
    if ($year == $cyear && $month == $cmonth) {
      # if yes, then add the $day to @days
      push (@days, $day);
    } else {
      # if no, then add the $days to @temp
      push (@temp, $days);
    }
  }

#while there are spare $days remaining
if (@temp) {
      my $new_c = new HTML::CalendarMonth(month => $cmonth, year => $c
+year,);
#Create hash linking $new_c and @days      
      %calendar = ($new_c => @days);

return @temp;

#when all $days are used up:
}   else {
    

  
    # Embolden headers
    #throw new calendar with @days
    foreach ($new_c{@days}) {
       $_->item($_->month,$_->year)->wrap_content(font({size => '2'}))
+;
       $_->item($_->dayheaders)->wrap_content(font({size => '1'}));   
    $_->item(@days)->wrap_content(font({size => 4, color => 'red'}));



    # Generate container table
    my $t = new HTML::ElementTable ( maxrow => 1, maxcol => 6 );

    # Populate container table
    foreach (0..$#cals) {
       $t->cell(0,$_)->push_content($cals[$_]);
    }
    print $t->as_HTML;


}

}
}

#There may be a lot of gobbledygook here but I hope it gives an idea o
+f what I'm trying to do with this approach.
#Other issue is re-sorting so the calendars are placed in the table in
+ order.
[download]

I think I have solved your problem jonnyfolk.

#!/usr/bin/perl
use strict;
use warnings;
use CGI qw( :standard );
use HTML::CalendarMonth;
use HTML::AsSubs;
use HTML::Element;
use Date::Calc qw( :all );

# @dates has already been sorted
my @dates = ( 730000, 731158, 731159, 731160, 731161, 731178, 735000 )
+;
my ( @cals, @days );

print start_html(-title => 'Calendars');

while ( defined $dates[0] ) {
  my $days = $dates[0];
  my ( $year, $month, $day ) = Add_Delta_Days( 1, 1, 1, $days - 1 );
  my $new_c = new HTML::CalendarMonth ( year => $year, month => $month
+ );  
  @dates = CreateCal( $year, $month, @dates );
  push( @cals, $new_c );
}

# Embolden headers
foreach my $calnum ( 0 .. $#cals ) {
   my $cal = $cals[$calnum];
   my @color = @{ $days[$calnum] }; # the days to be colored
   $cal->item( $cal->month, $cal->year )->wrap_content( font({ size =>
+ '2' }) );
   $cal->item( $cal->dayheaders )->wrap_content( font({ size => '1' })
+ );   
   $cal->item( @color )->wrap_content( font({ size => 4, color => 'red
+' }) );
}

# Generate container table
my $t = new HTML::ElementTable ( maxrow => 1, maxcol => 4 );

# Populate container table
for my $calnum ( 0 .. $#cals ) {
   $t->cell( 0, $calnum )->push_content( $cals[$calnum] );
}

print $t->as_HTML;

print end_html();

exit(0);

sub CreateCal {
  my ( $cyear, $cmonth, @dates ) = @_;
  my ( @day, @temp );
  foreach my $days ( @dates ) {
    my ( $year, $month, $day ) = Add_Delta_Days( 1, 1, 1, $days - 1 );
    if ( $year == $cyear && $month == $cmonth ) {
      push ( @day, $day );
    } else {
      push ( @temp, $days );
    }
  }
  push ( @days, [ @day ] ); # store the days of each calendar
  return @temp;
}
[download]

Hello, Mr Muskrat, sorry about the delay in getting back to you - I've been waiting for some time to go through this properly.

Firstly this is a definite solution to the problem - it is throwing the calendars, with their specific day arrays into a container table.
Secondly, I don't understand it!!

Well, there are one or two things that are new to me and perhaps if you have a little time you wouldn't mind explaining them to me?

In the sub CreateCal: push ( @days, [ @day ] ); # store the days of each calendar
you're storing an array into and array, I thought that would need a %hash. What is the significance of the [ ]?

After #Embolden headers, the line: my @color = @{ $days[$calnum] }; # the days to be colored
seems to be a hash of some sort but I'm afraid I don't quite get it. (I do get the fact that you are storing an array of dates and then extracting them, but I don't understand the mechanics).

I'm very impressed at the simplicity of what you have achieved compared to the Heath Robinson approach I had embarked upon - this looks like the real thing.

I have also been trying very hard to get the calendars to fill different rows:
the line  $t->cell( 0, $calnum )->push_content( $cals[$calnum] ); pushes all the calendars along a single row.

If we generate a new table:

# Generate container table
my $t = new HTML::ElementTable ( maxrow => 12, maxcol => 3 );
[download]

then how can I get the calendars to fill across and then down to the next row?

By using  $t->cell( $calnum, $calnum )->push_content( $cals[$calnum] );
the calendars fill diagonally, and I had hoped that by using

# Populate container table
for my $calnum ( 0 .. $#cals ) {
my $row = int(my $calnum/4);
   $t->cell( 0, $calnum )->push_content( $cals[$calnum] );
}
[download]

that might do the trick, but I am left with a blank screen. In fact everything I have tried pretty much leaves me with a blank screen!!

If you have any ideas on the latter and perhaps give an explanation of the former I would be very grateful

Many thanks, though, for your help so far...