The UK is an island. Large enough to be a nation, but still essentially an island. The daily temperature range is quite low compared to places far into the middle of continents. The air blows in, having traversed the Atlantic. Metal stuff here is ready to give up it's iron back into the ore like from which it came!
I have tried all sorts of things. When I can, I go for stainless. For all else, I protect. I use ACF-50 or the blue "Corrosion Block" grease, both from Lear Chemical. There is also a tenacious kind of industrial spray-on as used on oil rig platforms. I have some called Wynn's "Viscotene". It comes out as a pinkish white wet foamy that rapidly disperses into a very sticky stuff. It dries off, and from then on, it's hard to shift unless with WD or kerosene.
I have sometimes resorted to home-brew nickel plating. It's a messy chore to set up, and needs some care, but easy enough for anyone to do, and only uses common kitchen substances - and some nickel. The main work is in the preparation. Actual ingredients, and kit you need is very cheap. It absolutely works permanently. I have posted about it in
HM about it a long while back. The countershaft in the picture has been given 700mA plating out of vinegar solution for about 10 minutes. I'm lazy, so most times I reach for oil, grease or spray-on protective.
I also butchered some plastic 110mm drain pipe to make a plating bath container. I blocked the ends with those white stopper lids that are used to block the ends of cardboard shipping tubes. This one was to go around a South Bend spindle. Spindles are generally safe from corrosion, except for the precious MT3 taper up there. It's a great little plating bath, so that one does not need gallons of solution, but I still found it faster, and more convenient to just put the sticky oil up the taper.
I think I may follow the route
@DavidR8 took, going for a welded stand. It will have to be treated with primer and some tough paint. Dave probably used his mill stand as a welding experience skill-building project.
That would also be the case for me!