Can an ANPR plugin pass the number plate details via the SDK ?. We currently parse the 'MilestoneEventTypeMajor and 'MilestoneEventTypeMinor' in the XML config file

What you are looking for might be to read analytics events. Try to explore the Alarm and Event Viewer sample. The sample is standalone but the same methods could be implemented in a plugin.

If this answer is not a perfect fit for what you have in mind please elaborate. What is the ANPR and what should the user see or be able to do in a plugin? (For the Smart Client?)