Cupboard wooden 'lintel' - is it structural?

[SiD the Turtle]

Hi folks,

 

Got a weird one here. House is a 1930s semi. There are two bedrooms front and back, that are separated by TWO walls, as in the middle of them are two cupboards and the chimney. The chimney is out of use as both walls are sitting on RSJs when the walls below were removed in the 80s.

 

We want to repurpose the front bedroom's cupboard into a shelf or 'study nook' and noticed that above the cupboard door was plasterboard so we simply knocked it all out. Then we discovered that there were two substantial pieces of wood making up the cupboard frame, connected to the party wall and the chimney:

 

 

I want to cut this out, but checked in the loft first. The loft joists run perpendicular to these beams and are resting on the brick wall behind. My only concern is that the joists run all the way from the front of the house to the back are are actually two pieces of wood connected together through a join- that join sitting above the cupboard here. A diagram to help:

 

 

Can we remove this wood? If we do the front half of the two joists sitting on this wood will only supported by the adjoining joist, which itself is sitting on the brick.

 

Hope that makes sense!