Causing confusion as to origin is no longer the benchmark by which we judge whether a defendant has acted illegally. This is a welcome development.
These are your key terms to address.
You need to define the important terms by working through the statutes concerning Trademarks.
How do the rights subsist (work through the statute), and what cannot be registered as a Trademark.
Use case law to discuss and distinguish where confusion may occur and how the courts have interpreted this.
What was, and is, the 'benchmark'. Use case law to compare.
Discuss possible offences, infringements, then remedies for the Trademark owner and which are most commercially sensible.
Outline defences available to the accused.
Form an informed opinion using your commercial awareness and produce some advice.