Re Rendering over Lintel Timber

I am a total novice so please go easy,my outside render has several cracks,the house had settlement in the 40s but has not moved much since,after tapping an area between upstairs and downstairs window the render came of with ease,the bricks are spalling and some are loose, even though we have just had the wall ties replaced proffesionaly,that were recommended with an engineers report in march when purchased,i am confident i can do the job but what should i do over the timber lintel over the window,how do i render direct on to the lintel,also there is a large gap under the lintel to the window were a smaller window replaced the original,. no wonder the render fell of, with nothing to hold to,what would you suggest,many thanks Nat

e.m.l.

Expanded Metal Lath

cheers thanks for your help