The other day I was trying to do some research from prior Holt's auctions. When I clicked on their "Archive" link I got the following message:

Access Restricted
You are not allowed to access this page.
If you would like to get access, please contact our administrator.

A couple of days after requesting access, I got the following response: "You can purchase our Archive section on our shop."

Sure enough: Access to HOLTS Catalogue Archives - Holts Shop: Browse HOLTS online archive catalogues of every auction from December 2006. Access will be via "My Holts" and will appear as an extra tab once you have logged in. Access to the HOLTS online archives are only available via an individual subscribers "My Holts" account. Simply purchase this service and an email will be sent to HOLTS who will activate your subscription $46

I didn't realize Holts was charging for this service.