In your BM link Bernard, their 'Bibliography' quotes two pages from Jackson - Nos. 101 and 155, where the author provides a series of b. & w. pictures which are quoted as being from a 'James Powell & Sons 1880s
Photograph Album' - and these pictures would appear to now be in the possession of The Corning Museum of Glass. None of this information actually states metalwork by Powell, so wouldn't have thought the BM based their attribution for 'ironwork made by Powell' solely on these pictures, and think there must be more to it than this. Always possible there was/is additional text accompanying the b. & w. pix which not shown in Jackson.
Why don't you send the BM an email and request a little more in the way of positive information
