You will need to contact the owner's representative to arrange access.
In the case of this object this can be done by:
Writing to Mr James Carleton at Farrer & Co, 66 Lincolns Inn Fields, London, Wc2a 3lh
Reporting A Data Error:
Reporting An Access Error to the HMRC:
A rectangular plaque
Maker:  carvings, Ivory
Description: 
Ivory carvings: A rectangular plaque, possibly the centre of a triptych, carved in high relief with some figures completely undercut with the Deposition in the upper part and the Entombment below: in plain raised border, the undersides chamfered - 6 1/4in. by 3 7/8in. Italo-Byzantine, 10th/11th century
ID:  78229