Have a pair if castle richmond bookshelves myself. Sound signature of castles are classic british warmish signature. They were also known for their furniture grade cabinets, which were handcrafted in the uk.
However, they were bought out in 2008 by the IAG group, a chinese owned conglomerate which also owns the brands of Mission, Wharfedale, Quad and more recently Luxman. I have the last batch of uk-made Castles, and I suppose your pair is uk made as well, since IAG relaunched Castle just last year pero made in China na lahat pero still retaining the sound and premium cabinet construction.