UK 1927 Half Crown New Design

As pictured, I have a 1927 half crown which is to my eye of the "new design", however that was apparently only produced in 1927 as a proof coin, and this one is certainly circulated (the coin may have been struck as a proof and then leaked out, as do so many).

However, I am cautious about getting excited (story of my life). I have checked with Seaby, and they seem to think this design (fourth coinage new types 1927-1935) was only used in 1927 for a relatively few proofs (eg: as per https://en.numista.com/catalogue/pieces2754.html), any one got any more information?

Congratulations!

It's most definitely the KM835 and not the common KM830. Unlike the lower denominations, the obverse is little changed but the reverse has a markedly different shield with a pronounced waist and a monogram on each side.

Ignore the specs on the Numista listings which inaccurately indicate the Type IV is slightly larger and heavier than the earlier issues. It isn't, they were both minted at 14.138gr with a 32.3 diameter.

The only potential raincloud on this particular parade is a contemporary forgery so if you have a set of digital scales and calipers check the size and weight.

Tony Clayton has a picture of a very similar Type IV circulated proof here:

http://www.coins-of-the-uk.co.uk/pics/g5/hc/index.html