This is an episode of the British anthology series "Thriller" (1973) TV-Series 1973-1976, and was, I've read, the first episode shot. While the first season of that series is out on R2 PAL DVD, I watched it on a long out of print US video under the title "Carnation Killer." It lacks the Thriller opening.
It starts with a man walking up a set of stairs. We first see one of his arms thrust out in front of him, holding a bouquet of red carnations. We then see his other arm behind him, his hand gripping a woman's wrist, and we hear her struggling. She is seated at a dining table with a fancy setting, where she is killed. This is partly intercut with shots of a man pushing a baby carriage somewhere offroad. He pushes it down an incline towards a dumping ground, and a woman's body spills out (it doesn't look like she would actually have fit in the carriage).
Abruptly, the man is then exiting the trial where he'd been convicted of a series of murders by strangulation, in which he'd been nicknamed "The Carnation Killer." He escapes after the van he's in is in a collision.
Meanwhile, a man arranges with a solicitor to meet in a subway station. They've never seen him before, so he says he will wear a red carnation. You can guess where this is going....
A woman from the solicitor's office meets a man with a red carnation in the subway. It is, of course, the killer. She gives him a suitcase of money, and takes him on a train to see a house the man had inherited, where he is supposed to inventory its contents. The woman's boyfriend tries to meet her at the station also, but he arrives too late, and takes the next train.
When the man who'd really received the inheritance fails to meet the woman, he goes to their office, and they enlist the help of the police to find out what happened to the young woman. There are some echoes here of Psycho, I thought.
It's not bad, and it has a fairly dark ending. Pretty short too, only about sixty-five minutes.