I would stop short of saying a 16A fuse definitely complied, but I couldn't say that it didn't comply either. The 16A breaker is mentioned in the OSG (in the 17th edition too, so it's not a new thing), being an IET publication we can assume it carries some weight.
That indicates it
does comply, but the appliance has to be
permanently connected, not via a disconnecting device of any sort (a socket that is commercial or domestic). The picture you posted in your first post does state so.
But as other have noted, a look at the ring and its loading, it essential.
It was noted in previous posts that a 16A radial can have a 16A commercial socket directly off it giving a disconnection device.
I also noted in a previous post, that changing a 32A mcb for a 16A on a ring gives the same result, in that a commercial socket can be fitted directly onto the 16A ring. Of course the loading of the ring would need to be assessed, as per normal. I know my 32A ring could be dropped to 16A without any problems, as little is taken off it - TV, lap top, phone chargers and the occasional vacuum cleaner.
So, as been gleened so far:
1) A 32A ring
can have a 16A appliance off it, with the appliance:
a) only being
fixed;
b) with an isolation switch;
c) with a 16A fuse.
2) A 16A radial can have a 16A appliance off it with a fixed appliance or off a 16A commercial socket (the only 16A sockets available in the UK).
3) A 32A ring can be re assigned to 16A ring by a mere change of an mcb/rcbo. The appliance can be fixed or with a 16A commercial socket. As per the 16A radial.
Any constructive comments?