[Hampshire] Exim config

Hi,

I'm not sure if I'm being stupid and missing something fundamental, but
I'm trying to refine the AutoAway router I've got in Exim.

My aim is to get it so that it only responds if the current address was
the original recipient, and not when the current address is a child (eg
as the result of a forward or an alias).

vacation_director:
   driver = accept
   domains = ${lookup mysql {Q_ISAWAY}{$value}}
   condition = "${if and{{eq{$original_domain}{$domain}}\
      {eq{$original_local_part}{$local_part}} } {1}{0}}"
   transport = vacation_autoreply
   unseen

Unfortunately this isn't working. For example if I have:
     info@???
forwarding to:
     person_a@???
     person_b@???

If person_a has their autoaway option turned on, the router invokes when
the original email was to info@??? as well as to person_a@???

What I'm looking for is for the router to only invoke when the email is
directed to person_a@???.

Thanks,
Tom