Caro Peacock’s novel Death at Dawn (HarperCollins, 2007) is the first in a proposed series of historical crime novels featuring the heroine Liberty Lane. The book is set in 1837 and is a well written historical thriller introducing, among other incidental characters, a young Disraeli. The second book in the series (Death of a Dancer) is scheduled for later this year. The book has been released in both hardback and paperback. The hardback run has been modest, and signed copies are uncommon. Currently the signed hardback is available on ABEbooks from £50 up, but you could still pick up a copy from Goldsboro books for £25 if you are quick. Alternatively an unsigned copy could still be bought from Amazon UK at £20. The Goldsboro option looks good value - if the series takes off this is likely to represent a very good investment.
Caro Peacock is is fact Gillian Linscott, and has published a considerable number of books under her earlier name.
Update: March: Don't think this ever really took off - plenty of signed firsts available, though starting (optimistically) at £30
Death at Dawn (HarperCollins, 2007)
Death and the Dancer (HarperCollins, 2008)
A Corpse in Shining Armour (HarperCollins, 2009)