Nothing to do with how many angels can dance on the head of a pin.
Resicast have released two kits in 1/35 scale: 18pdr, and 18pdr & Limber
http://www.armorama.com/modules.php?op=modload&name=News&file=article&sid=15627&mode=thread&order=0
http://armorama.kitmaker.net/modules.php?op=modload&name=Reviews&file=index&req=showcontent&id=9618
Don't mean to be picky but the barrel looks a bit underscale to me - on the 18 Pounder Mark I the barrel and receiver were about the same diameter.
Here's a Mark I (1906) at Fort Lytton.
Regards,
Charlie
The model looks more like a Mk II to me, in which case I'd say the barrel is about right:
http://upload.wikimedia.org/wikipedia/commons/5/5b/SANMMH_-_QF_18_pounder_Mk_II_-_001.JPG
The Resicast site indicates the kit is supplied with both barrel types; an appreciated bonus. It appears they've gotten everything right with this kit; to include correct wheels and an ammunition caisson.