Safety margins around a gas cooker please. I am replacing a electric cooker with gas

Unless stated differently in the manufacturers instructions, your "Hot-Zone" clearance must be 760mm above the gas burner. (Take the measurement from the burner cap) So as it stands now without you looking at the manufacturers instructions, which are included in the appliance hand book this would cause an illegal installation due to the wallpaper being classed as flammable. Add additional rows of tiling to sort this or and remove the wallpaper Take a look at this page on my site, it should explain things more clearly https://fixcookers.co.uk/website/Install_Hotzones.html Point to note, some manufacturers have a lower clearance, some Stoves/Belling/NewWorld hobs only need 650mm