Small Letter in Plate?

[Ryanfaescotland]

Now this is something I have never saw before. Took me right by surprise so much so I even stopped to talk to the car owner. A small letter in a licence plate? Her plate read along the lines of

WiLU 435

couldn;t get a photo though since well she was there and when I spoke to her she didn't seem impressed. Told me she's never had trouble from the police (that was my opening question probably why she wasn't impressed) and that's pretty much all I asked.

 

[M21MFS]

Can't see how that plate is legit????

If it's Irish for example, it'd be something like DAZ 1234 (3 letters, 4 numbers) it doesn't look like a legit UK plate either??