Just to update this thread the sill jacking pad arrived this week but there may be a problem. The listing on ebay was for the pad I posted a photo of above (in fact I copied the photo from the listing) and it has a recess in it to receive the dimple on top of the scissor jack. This is how the others on my car are.
However, what arrived was this. Not only does it not have that recess but it seems to have a protuberance which would actually prevent the jack from engaging.
Before I return it, am I missing something here? This seems to be the completely wrong part.