Another John wrote:

... when I come to clean the white-work(?) of our new porch, built last
year, is there anything that can be recommended to clean it well? Or do
I just use car shampoo or something similar?

Of course I'm aware that various specialist cleaners exist, and indeed
I'm happy to buy one of them, but I'm wondering if they are simply
expensive "snake oil".

They are excellent.
Around £5 for a litre. It really does make upvc come up like new.
I tried the 'No-nonsense' one from Screwfix, but found that wasnt as
good as the one I get from my local plastic supplier. Cannot recall the
brand now.
Alan.
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