Hmm. So we have observed one in the National Portrait gallery. My guess is the original, as stated. NPG6049; rectangular image, dark surroundings, thickish paint. Inscription. Acquired 1989 from a Brown descendent.(detail – my image)
There is also a copy or ‘after Dance’, acquired much earlier. NPG1490, acquired 1908 from one Warren Trevor Esq. It has an oval visible canvas, thinner paint; canvas character visible.(detail – my image)
There is one at Burghley, which is shown in two web images. Jane Brown’s biography refers to the Burghley portrait sitter’s jacket as in ‘a sober green’.
There was also recent TV coverage of Belvoir, where a Dance hangs behind Alan Titchmarsh. Here is a screen grab; Karen Lynch of Yorkshire Gardens Trust identifies that it is the same frame and panelling as our Burghley above, but with television lighting:There is an image on National Trust’s main web site which is much more ‘polished’ (did they use lip gloss in the 18th century? or LED spotlights?) and does not appear to be any of the former. It appears to be at Wimpole, here.So that is four. Are there more Dance copies out there? Please make contact if you know of another location of a permanent work akin to these, as an inventory in 2016 would be a fine achievement if it does not exist already. Their lines of provenance may indeed give clues to the degree in which the portraits were originally valued or even hint at how and when they were created… as well as when and if they were restored.
Note: the use of photo editing and management by website staff may mean that generalisations are made here with images that are in easy public web access. Access to the originals is the only way of judging properly – seek out the works and study them. The Dance original will be travelling from NPG, London (not currently on view) to several locations during the 2016 Tercentenary. Get thee to Harrogate for 24th June!