The other option is a spirit based wood preservative which includes a
oil/wax protection. Those give a flat colour look, but also impart some
water repelling properties. (I tried the Barrattine wood protective
treatment (Toolstation) last year on some outside furniture. Been quite
impressed with that - it all held up nicely though the winter, and is
still water repellent)

John how good is the UV repellent in it. SWAMBO quite likes the finish of the pressure treated wood of our garage so it has had two applications of a clear treatment but this has no effect in preventing the bleaching of the timber. Does the UV repellency only apply to the coloured versions and the dyes used in them?

Richard