Update. Well after a couple of weeks it appears to be working, I haven't done much mileage wise (lockdown), but a trip to the shops (essential items, potatoes, peas, Brandy, Magnums etc), is a round trip of 36 miles and my wife eats a great number of Magnums so... Yup car looks greatly clean (baring the dust), seems well worth the effort. Treated the windows with the rain piss-off stuff that I bought around 12 years ago and filed away on the back shelf of my shed, again pretty good but suspect it may have aged a little, and unlike your Vin Rouge I don't think aging does it any good, may invest in a new bucket when the raps come off.