ITV "Unforgotten" features man killed by fountain pen 35 years ago!

[Chrissy]

We're watching the latest series of ITV's 'Unforgotten" and when we watched episode 5 from Monday evening we were surprised to find that the man who was killed 35 years ago was killed by being stabbed by a fountain pen.
They even mocked up an online picture of a non-existent fountain pen brand to show what type of pen it was. On the mock up there was a pen that looked similar to a Parker Sonnet. The actual pen that was 35 years old and was found embedded in the man's skull that had been frozen for many years, then thawed out, looks like something in between a Parker and a Waterman but is difficult to pinpoint.

Anyone else see it and have any ideas? https://www.itv.com/hub/unforgotten/2a3372a0023