Email invoice - how to include custom field?

Hello there

Quite a simple question, but I've tried for ages with no success...

I created a custom field for my customers (just added a simple radio button option 'age: adult/young')
I need this to show up on the email invoice sent out to me

How do I do this? Really grateful for any help as I am struggling.

v 2.0.1.1

Many thanks
cheers
steve

Hello again
Ok, if it isn't possible for a direct 'solution', would it be possible to help me track down a way..

Do I find out the entry in the SQL database for the custom field (how do I go about that..?!)
Then do I insert it in the .tpl file:

admin/view/template/sale/order_invoice.tpl

say after the 'telephone' entry:
<b><?php echo $text_telephone; ?></b> <?php echo $order['store_telephone']; ?><br />
but substitute the '$text_telephone' and '$order['store_telephone'] bits for the new field name?

Not sure whether I'm on the right lines at all?

Thank you
Steve

Did you solved this? I'm interested to do the same thing.