Rare in America; there were ton's of small anvil making shops in England over the years and very few of them exported to the USA. However they may be fairly common near the factory in the UK. Just like common US brand anvils tend to be uncommon in the UK.

well it's taken a few real heavy hits with my 9lb hammer with no scuffs or marks of any kind, so I am happy with it.

I'd take care with that heavy a hammer on that small an anvil---mistakes could be "unpleasant"!

I generally size the hammer to the anvil though I do have a "rare" Powell anvil that we often overamp as it has already lost the heel, (Nice Face, fair horn, was $40 for an anvil over 125#!---it's my "loaner").

When I teach I often take a piece of soapstone and mark the sweet spot on the small travel anvils so students don't miss-strike as much.