Not sure which bit you can't locate, I used this link from IET; 18th Edition of BS 7671: send us your feedback - IET Electrical - http://electrical.------.org/wiring-matters/64/dpc/index.cfm
then 'log in' below Comment on. Whatever way you do use, when in the BSI web site search for - BS 7671 - (need the space between BS (&) 7671).
Stand corrected Andy, have 'may be' in my notes, but see that it is 'shall be'. Must of had too many Gins
In any case it needs further clarification, as alluded to by the many comments. I get side ways looks from my customers, when I suggest their bonding needs upgrading, when replacing a luminaire for them. They are going to think I'm a right rogue, when I spend half a day putting in some new earth rods