Trying to identify a British Short Film

I am trying to identify a British short film of the 70s or 80s. It accompanied a main feature in the cinemas, but I can’t remember which one. This is as much as I can remember:

1. A WWII plane crash is discovered in a field and excavated. This is in the East End of London.
2. Under the debris, the excavators find the skeleton of a murdered woman whose body was put into the hole before it was filled in during the war.
3. The police investigate and it appears that a pregnant WWII refugee had gone missing around that time and people thought she had just moved away.
4. Investigations lead to a man who knows what happened, but he is now an 80 year old, living in a home with dementia.
5. The police discover that the woman who is visiting the man and calling him dad, is the daughter of the murder victim.
6. Knowing they are unlikely to get any clear answer and are more likely to upset the woman, the police drop the investigation.

Someone said they think it sounds like an episode of ‘The Bill’, but since I never watched it, I don’t think that is what I am looking for.

Any ideas?

Many thanks

Jon