Ann: Preliminary Profit Advice - Half Year Ended 31 December 2016, page-23

Well, my knowledge on blockchain is not great, but I'll comment based on current understanding.
Basically, it's a way of decentralizing the list of transactions and provides a method of authentication (i.e. the person you're buying from is real, because the link to previous blocks in the chain are valid).

Applying this to registries, it would mean the registry database is no longer centralised, but each block in the chain is distributed. You still need the mechanism (software) which will perform the authentication using this concept, along with the someone to write/update this software.

How the broker and/or investor interfaces with this software is not something that's clear, although I'd imagine an API of sorts (RESTful service perhaps [basically a bunch of HTTP calls that are 'stateless']) would perform this function.

If it did occur in this fashion, it wouldn't really change the registry function hugely, other than to minimise the infrastructure requirements of the organisation (remembering blocks in the chain are distributed between participants, instead of centralised on a database). But as I said earlier, I have never written anything using blockchain, so I could be completely wrong.