Yes, it's a ring circuit. I'm not sure why the knockout box has a conduit stub on it, if I get an opportunity I'll have to have a look.
Yes, all BS1363 plugs have a BS1362 fuse in them, even those on extension leads. That is what makes the ring circuit system particularly safe, in my opinion.
From memory, I think that might actually be a fridge plugged in there. Most appliances come with molded plugs these days rather than hand wire types, whereas extension leads have hand wire plugs.
Maybe the boiler should really be on its own fused switched spur outlet?
