Google hasn't helped me on this occasion.
If so, do you have any details of the "L" number it carried and/or any pics of the vehicle please?
I bought one recently to go on a "breakdown train" I'm making, but it is devoid of any decals.
I can only ever recall older type "L" carriage stock such as dog boxes being used.
It's no big deal, just curious.....if nobody knows anything, I will just make-up a number before I weather it.