Bought some 220, 400, 600 & 1500 grit sand paper and some stainless steel cleaner/polish...along with four king size Redbull.
Before & after shots below. I've left the top of the neck area for now as my hands are fooked! One pipe down, one to go...
Before:
After:
A tip for anyone doing the same; only use 220 grit on the REALLY tough areas as it its quite hard to buff out with the finer grit papers.