Curious Planning Laws for Fences, Trellis and Pergolas?

Hello

I've been reading about the planning laws for fences, trellis and pergolas and just wondered if I am understanding this right...

At the moment I have a 6 foot garden fence and for privacy have attached a 1 foot trellis to the top. Strictly speaking this is not within planning laws since they state a fence should be no more than 2 metres (6ft 6"), and so my fence is about 6 inches too high. I presume this won't cause a problem unless a neighbour complains to the council...

However, if I erected a trellis screen just behind the fence, or built a pergola and grew climbing plants up it, this could be up to 2.5 metres (8ft 2") tall and that would be fine...

So essentially you can get around the 2 metre limit on boundary fences by build a higher structure just behind on the basis that it is an ornamental garden feature or plant support?

Thanks for your advice