I haven't heard visibility splays at road junctions called public amenity space before but if the visibility splays were shown on your plans can't your architect and planning consultant advise on simple things like suitable boundary treatments that maintain the sight lines?
What does the 'stopping up order ' mean ?
I'm not saying all visibility splays are public amenity land. It is just that the poor old OP has had rather a tough time of it with the Planners and I didn't want them spend a shed load of money creating a lovely front garden just for the Planners to come along and spoil the party. I was merely suggesting they check to make sure it is deemed to be garden land/private amenity space. It is one of those Planning minefields that unless you have stumbled in to it before it never occurs to people.