Furpho, the "EML" that NickB mentioned is better known as "wire lath". It's galvanised, and comes in 8ft x 2ft sheets. For your job, I reckon one sheet would do, around £12.00 per sheet. The lintel above the door looks wooden, so you would DEFINETLY need wire lath over that, also, as Nick said, there's a crack on the left side of the blockwork. With that crack, i'd chisel it out a little, point it up with a bit of cement, fix wire lath ove the whole area, the coat it out with Bonding, let it set, then multi finish, job done. Let it dry out, seal the plastered area with watered down matt emulsuon, 2 parts paint, 1 part water, then it's all ready to paper or paint.
One other thing, sometimes when you have old brickwork, a scratch coat of sand and cement to seal in the old before you apply Gypsum plaster, helps to seal in any salts etc that might be in the old brickwork, that might come through the Gypsum plaster.
A lot of info here, but worth a read.Let us lnow your thoughts mate.