I've only ever designed a couple of letterhead templates throughout my design career so far, and neither of them required continuation sheets.
The front page of the one that I'm designing, has the company logo + contact details in the header, and then the company registration number + address in the footer.
I'm wondering what the standard approach is for the footer for the continuation sheet... should this contain the address like the front page? Or should I leave it blank?
As for the header of the continuation sheet, this uses a graphic device taken from the logo (without the contact details that are on the front).