SA Requirements earning over 100k on PAYE

Scenario:

A Client has been earning over 100k under PAYE for the last 5 years.

Question:

1. Should HMRC have notified this person that they were required to submit a tax return (when the requirement to file a tax return for PAYE earners above 100k was introduced)?

2. Does the client have scope to argue any interest and penalties, if they contact HMRC and explain the fact they should have filed Self Assessments for previous tax years?

3. What tax year was the legislation changed whereby earners over 100k on PAYE were required to submit a SA?