WW1 British 4.2inch Howitzer?

[Peterem]

I'm having trouble tracing prototype information or pictures of a British Great War 4.2inch Howitzer (Code BP13). Everything seems to default to the 4.5 inch model represented by BP9/9A. Does the code represent a captured German 105mm?  Any help appreciated.

[fred.]

I think I asked about this before. But I can't remember the answer... 

[fred.]

Google is your friend, when your memory isn't.

http://www.pendrakenforum.co.uk/index.php?topic=7643.30

Dave says that the 4.2 one is a mistake

[Peterem]

Thanks Fred, that's saved me any more work. I wonder what it's meant to be...