We've all heard of BSP; British Standard Plumbing thread. And of course BSW; our old friend British Standard Whitworth. God love it.
I however wish to propose the existance of another in this venerable line. BSH. The British Standard Hand. BSH defined the tolerances requried to install any part on a British made car from the 1960's.
Despite drawing a blank in my research (BSH docments are presumably still protected by the National Secrets Act) I have been able to infer the following about the BSH:

1. It is considerably narrower and flatter than my hand, and can be inserted easily and painlessly into the most inconvenient of spaces.
2. The wrist joint is capable of greater range of movement than mine. I estimate a BSH wrist can flex and extend at least 45 degrees more than my wrist, and supinate and pronate over 180 degrees, allowing the hand to completely reverse, in either direction as required.
3. BSH fingers are all 10" long, have an extra joint allowing backward movement and can exert a pressure of 300 lb/in. They can be folded out of the way when not in use.
4. BSH hands are impervious to heat, cold, grease and cannot be cut or bruised.

I changed the speedo cable today.  Here's a photo of the 90 degree elbow through the 3" hole in the gearbox tunnel.  As Jarrod pointed out; at least there's a hole.