Mrssiren | - Dee Siren - Bbc Surprise

Another angle: sometimes names in reports can be part of a project or a brand. Could "MrsSiren" be a brand or an alias used by someone working with the BBC? Maybe Dee Siren is a character in a BBC show, but I'm not aware of such a show. Alternatively, there might be a podcast or a YouTube channel that was a surprise success on the BBC platform.