I had a company in Dartford try to powder coat these items twice and made a really bad job of them. Fortunately I got my money back and choose another company based on this thread.
My frame, forks, stem,seat post clamp and dog collar arrived back from 3 D Finishers in Coventry today. http://www.3dfinishers.co.uk/
To say I am impressed is an understatement. The finish is top notch, the coat of lacquer really helps bring out the colour. There was no need to clean any threads at all. He used a bottom bracket and headset cups and knew exactly what not to powder coat.
Dave also recorded the frame number and took photo's of the whole process. I wish I had known how good the frame looks after media blasting, I like the natural steel colour.
£35 to media blast and coat all those parts to that high a standard is going to be hard to beat.
A big thank you to Dave @ 3D Finshers for getting it right!