Another UK member to add to the list.

Based in Central London, I used Ace Acton (Acton, W.London) for the first service, but found them lacking in any enthusiasm for anything ever since they downsized and lost their franchise (shame, they used to be really good).

I now use Hunt & Keal (a name that makes an interesting spoonerism) based in Park Royal, W.London. Kind of pricey but they know their stuff. They used to be part of the Hooper empire and so you will still find a collection of custom Rolls and Bentleys in their shop... and if it's good enough for rich folk it's good enough for me!