Going back to my original post...
I received an email today entitled "Congratulations On Your Tier Upgrade" confirming Gold status (woo hoo). It took six working days (or possibly five if you count the Wellington Anniversary).

The email said this...
"Your new membership pack will be with you in the next few weeks, but in the meantime we wanted to let you know of the additional benefits your new tier status provides, which are available to you immediately."

I'll try to remember to update the post when my membership pack arrives.