Here's one that maybe somebody could throw some light upon. My S type is year 2000. The last numbers on the VIN plate read FL54054.
I thought the number would have been M. . . . Am I missing something or just plain daft..???

 

No, it's just that L is before M. Even later cars are N.

 

The L prefix is correct for the 2000 Model year as JagV8 pointed out... when looking for parts - the sequence you need to be concerned with is the last 6 digits of your VIN - L54054 in your case...