Hello Julian, thank you for your comments. I made the Archlute for Penny Olver in 1981. It seems a long time ago now, and I am very pleased that is is still going strong! According to my records it was my 113th instrument, and was based on an original by Matteo Sellas, Venice 1531, in the Victoria and Albert Museum.
You ask about the wood used in its construction. The soundboard is European Spruce, and the ribs that make up the back are English sycamore. The pegbox is also sycamore. The pegs and fingerboard are ebony, and the back of the neck is veneered with Macasser ebony. The finish is French polish, though the soundboard is most likely just sealed with a home-made egg-oil emulsion.
I sold the instrument for £700 in 1981, but have no idea of its current value, having lost touch with the field of early musical instruments when I moved on to do other things a few years after your Archlute was built.
It is interesting that Penny referred to it as a Theorbo. At the time a Theorbo was the name given to instruments with longer string lengths than Penny's instrument. But I don't know what current thinking is on this.