That's only a building regs requirement, not a wiring regs requirement. Unless this is a new build or extension, the kitchen will not be subject to building control approval so you can ignore that and put it at any height you want.Personally I would go with the OP's drawing in post #19 above.
For the record I purposely deviated in my own house and have the cooker switch directly above the gas hob. I has not melted or caught fire, and indeed if I want to I can reach over the pans boiling away on the gas hob and turn it on or off without my arm catching fire contrary to popular belief.
And why did I put it there? so when I want to use something like a Gorge Forman electric grill or an electric chip pan, I can stand it ON the hob (on a chopping board) and it's under the cooker extract fan. They have such a silly short mains lead that if I just plugged it into one of the sockets either side of the cooker it would not reach under the cooker hood so the fumes would not be extracted. So having a cooker switch with a built in socket right behind the cooker solves that issue.