The studio system certainly had its merits. Hopelessly compromised budgets meant that an unheralded character player could be given the chance to shine. Neglected Henry Daniell, previously responsible for a terrifying Brocklehurst in Jane Eyre and a reptilian Moriarty in The Woman in Green emerges triumphant here. This is Daniell’s finest hour in the movies, and he enacts the tragedy of Dr MacFarlane with incisive, malignant brilliance. Roy Webb’s musical score, a haze of moody Scottish ballads, marks this out as an unusually emotional horror story.

Such melancholy is fitting for the final screen confrontation of Karloff and Lugosi: Karloff, ablaze with Hogarthian glory and exalting in the skin-crawling malevolence of Cabman Gray, and Lugosi, wasted by morphine but never less than effective as the caretaker Joseph. So literate is the script that it would work perfectly on stage; a fine testament to a haunting character study.