From you reply it appears that the wall is not load bearing. You can certainly check this by looking up in to the ceiling via that gap and making sure that you can't see lots of joists ends but can see the side of a joist each side of the gap running parallel to it.
But the next big question is - what the hell is that timber doing fixed below the ceiling like that? The answer should be "nothing", in which case why has the builder put it there and not up in the ceiling void to give a nice flat celling.
But the next big question is - what the hell is that timber doing fixed below the ceiling like that? The answer should be "nothing", in which case why has the builder put it there and not up in the ceiling void to give a nice flat celling.
