Michel Parry – Countess Dracula (Sphere, 1970)

Michel Parry Countess Dracula
Blurb (from Beagle edition)
The Countess was old. But she had discovered the secret of eternal youth – a secret which spread death and despair among the peasants on her estates. After her husband’s death the Countess quickly chose a young lieutenant of the Hussars to take his place in her bed.
See the Countess Dracula thread on the Vault of Evil forum.