Just a Matter of Time is a 1973 thriller novella by British writer James Hadley Chase.
She had been a popular pianist, and now has retired to live in a penthouse with a chauffeur named Bromhead, who serves her impeccably.
Her financial matters are handled by a banker named Chris Patterson, who does because he knows that Miss Morely-Johnson is fond of him and gives him costly gifts.
What Patterson does not know is that Sheila has been fixed beforehand by Bromhead, who plans to execute the perfect crime of killing Miss Morely-Johnson and making it appear like an accident.
The plan begins to go awry, though, when the detective on duty in the penthouse senses something fishy about Sheila dressing up as someone else when leaving the flat.