Well, here is an update. A bit lengthy as I want to cover the stages I tried. First of all I do not install third party free scenery from flightsim.to or elsewhere. I find that the quality of these often doesnt look great when you get closer. Also as MS keep warning with every update that you may have to disable them, I rather stay clear. So my Community folder only contains Liveries. Still, going through all the options I renamed the community folder and made a new one, empty. Flew from Hope,Hope to Vancouver international (I recommend this short VFR flight by the way, brilliant) landed and taxing to the stand as before, a CTD. I had also increased the size of my paging file to recommended 1.5x and 4x so that wasnt a cause either.
I then disabled my Touch Portal that I have completely configured for MSFS and again, this time to my relief as touch Portal with MSFS is so totally brilliant, a CTD at the final taxing stage. So Touch Portal wasnt the problem.
I considered next to delete the Vancouver airport I bought via Market place (I only install scenery I buy on Market place) but thinking about it there was still one other common factor, the taxing, blue arrows assist.
I decided to switch that off.
No CTD. !
This does not mean that taxi assist (blue arrows) is faulty. However I note that Vancouver International from Market place is an upgrade from FSX or P3D. So I wonder if the combination of some elements of the older technology with the new MSFS marshaling animations etc causes a problem ? I just dont know.
I may be totally wrong here and one suggestion read here about rolling cash is also worth bearing in mind.
I am still not convinced I cured it, although so far, so good.