Andy Burns wrote on 17/08/2019 :
So far I don't make use of it, but it lets you give access to your account(s)
to other systems, e.g. I think my barclays app on the phone could show the
balance of the santander account.

I was offered that by one bank, separately - it wanted me to give it
access to my other accounts. I imagined that was something other than
the 'Open Banking'. I declined it.