Apologies, you were correct, the script:

#!/usr/bin/perl
use strict;
use warnings;
use XML::Simple;
use Data::Dumper;
use LWP::Simple;

my $Document =XMLin("foo.xml");

while (my ($key, $val) = each %{$Document->{Placemark}})
    {
    printf "%s is at %s\n", $key,  $val->{Point}{coordinates};
    }
[download]

does work. I had updated incorrectly the XML file, thankyou for that.

Now that I can get the info from an XML file stored locally I tried to get the file when stored on a web server.
I used this script but it says that the file does not exist!
Any clues?

#!/usr/bin/perl
use strict;
use warnings;
use XML::Simple;
use Data::Dumper;
use LWP::Simple;
use XML::Parser;

my $url= "http://xweb.geos.ed.ac.uk/~s0341330/foo.xml";
my $foo = get ($url) or die "I can't get the feed you want";
my $parser = XML::Simple->new( );
my $Document =$parser->XMLin('$foo');

while (my ($key, $val) = each %{$Document->{Placemark}})
    {
        printf "%s is at %s\n", $key,  $val->{Point}{coordinates};
    }
[download]

Many thanks

Niall