Inquiring about a UK altarpiece

I don't really know where to start this search, so I may as well do it here. I'm trying to locate an altarpiece that in the 1800s (or early 1900s) was sold from an old chapel in Norway, probably to the UK - or possibly France. If UK, a Blackwell family may have been involved in the transaction. The altarpiece origins from the 1000s or 1100s. The intention is NOT to bring the altarpiece back but to get a photo of it for having a copy made for a new chapel. DO YOU KNOW OF OTHER NEWSGROUPS OR SITES WHERE I HAVE A BETTER CHANCE OF FINDING THIS ITEM ?
Thanks in advance for any help you may provide. My e-mail address is: aranden (at).online.no

Regards,
Arne R.

PS. BTW, here are some details by the door of the chapel, from the same era as the altarpiece:
http://home.online.no/~aranden/portal2.html

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