For people in the North of England I can recommend two metal finishers. Niphos metal finishing in Crewe and Derby Plating services in Derby. The people are Niphos are probably the most friendly to individuals, both have finished car and bike parts for me including hard chrome plating of wheel dropouts. Both are expensive as are all chrome platers, hazardous substances waste disposal prices have rocketed, man at Niphos joked that he was in the wrong business.
I agree with the recommendation to use C&G Finishes if you live in the North West, if you call in you will see Hetchins frames in for work, I believe he does them all. Owners of Vincent Black Shadows and other motorcycles of astronomical value send their work to C&G, traditional stove enamel at its best.
Many moons ago a friend had a Mercian frame refinished at Bob Jacksons complete with lug lining and barber pole over the top stuff and nonsense. The quality of finish was very good and the lining work as good as I have seen. It was expensive but that would be down to the hand painting after the base coat.
