[DanBC]

Watching anything on BBC iPlayer, even catch up programs, no requires a licence.

The BBC iPlayer service will warn you about content that needs a licence - it will ask before playing "do you have a licence?".

> every month I get a threatening, amateur looking, in red writing

Have you told them that you do not watch tv as it's broadcast or anything on iPlayer? Once you tell them they should stop writing to you for two years.