Advice on window frame construction

[mj007]

I am having a room re-plastered in a house I am renovating for rental. The plaster is old and has been taken back to brick.

The exposed brickwork now shows an unusual arrangement around the window. To my untrained eye, it looks like a previous owner has attempted to reduce the size of the frame by adding a layer of bricks to the sides of the frame and a piece of timber horizontally underneath the lintel.

Before I start removing it and replacing it, am I correct in assuming this provides no support? Any suggestions? Pictures are attached.

 

[vinn]

Presumably, you originally had double hung sash frames: the brick infill at the reveals is merely filler, likewise the horizontal timber below the lintel.

Best have 4 hands when removing the side bricks - and then the timber filler piece.
The lintel should be examined for decay at both bearing ends.
Do you have an outer lintel or a brick arch?

 

[mj007]

Presumably, you originally had double hung sash frames: the brick infill at the reveals is merely filler, likewise the horizontal timber below the lintel.

Best have 4 hands when removing the side bricks - and then the timber filler piece.
The lintel should be examined for decay at both bearing ends.
Do you have an outer lintel or a brick arch?

Hi, yes. Other houses in the street have double sash Windows. There is an outer lintel (i had in replaced with a steel angle due to decay.

If the side bricks and timber filler piece are not required, would a timber frame be a suitable replacement?

 

[vinn]

You had the wood outer lintel replaced with an angel iron lintel?

Presumably the nibs of brickwork that the original frame was fixed behind are still in place - if so you can easily locate a timber framed window in the original sheltered position behind the nibs.
Note how any other retro-fits have been done in the street.

If you have any kind of cavity then photo it & come back here.

Edit 06/07/2016 @ 22:16
Its just occurred to me that the "timber frame" you referred to above is just that: a timber frame for surrounding the PVC frame - not a timber window frame?