Yes indeed it should be UTF-8 but we've already established that the file has "strange" (being polite) encoding...

$| = 1;
$/ = undef;
print "Reading JSON file";
open my $fh, '<:encoding(UTF-8)', '../data/publicextract.charity.json'
+ or die "Unable to read Charity JSON File";
my $data = <$fh>;
close $fh;
print "...done\n";

$data =~ s/^\x{feff}//;  # Strip off BOM

print "Decoding JSON file";
my $js = decode_json $data;  # line 24
print "...done\n";
[download]

This takes about 10 minutes to read the 462Mb JSON file then fails with Decoding JSON fileWide character in subroutine entry at import.pl line 24

Given the time taken to open the file in UTF-8 and the error, I am thinking there is some nasty encoding hidden somewhere in this file

UPDATE

Changing the encoding like so

print "Reading JSON file";
open my $fh, '<', '../data/publicextract.charity.json' or die "Unable 
+to read Charity JSON File";
my $data = <$fh>;
close $fh;
print "...done\n";

$data =~ s/^\357\273\277//;  # Strip off BOM
[download]

"Strange" because the error doesn't include at import.pl line 24!

Another UPDATE

It seems I might be running out of memory...380400 records in the JSON file seems to be too much...