The use of any of these articles depends on the context, which you do not give. For example.
We spent the day with Hilary and Bill on their ranch. The former President was in a jovial mood...
Former President Bill Clinton today announced he would back the nomination for the candidate from ....
Jospin, a former MP, is seen here... (one of countless MPs throughout history)
Jospin, the former MP for Chipping Norton under Marsh, said the nude girls in the photographs were artiste models he engaged for his private oils on canvas painting class.
- For Teachers