Thanks for these replies, food for thought. I can’t fix a frame to the floor as there are pipes running there. Ceiling might be possible, will need to locate the joists.
4" at one end tapering to nothing at the other - 3.3m wall length. Two 4x2, two 3x2, two 2x2 and then dab/dot the cement board at the 'narrow' end. There are a load of pipes behind the plaster there which complicates things a little. Above the splash-back I'll screw a sheet of ply to the frame...
I need to attach some studs of varying depths to a plastered brick wall to build a frame that is square with the rest of the kitchen to attach wall cabinets and splash-backs. The wall is the party wall in a victorian back-extension with very poor looking bricks and a thick base coat (at least...