Please can some one explain how the "scoring" process works and what score I should be looking for when buying a German Shepherd pup. alan.deacon1@ntlworld.com

it is not the pups hips that are scored it's the parents that should be.
Ideally the figure should be below the breed average score, Your vet or a GSD breeder should be able to tell you the average score.

The hips of the animal are x-rayed and then sent to a panel at the AHT who score the plates on a few different points, they then score each hip left and right.
You need to add the figures together to get a total for both hips ie.
if a score of 6:6 (left and right) the total is 12.
your average will be a total figure too.
Most reputable GSD breeders will only breed from stock with well below average scores.
Ask them what the scores of both parents are.
Don't forget to ask about other hereditary defects too.

I have a booklet which details the hip scoring scheme, if you want one send me your address. It is illustrated with hip x-ray plates.
Basically the scheme referred to by the previous poster, is the British Veterinary Association hip scoring scheme, and is scored by specialists at the BVA, not the AHT. Both parents should be hip scored prior to breeding. To hip score a dog, the dog is x-rayed, the resulting x-ray plates are sent to the BVA. Each hip is assessed separately, and given a score from 0 to 53, the scores of both hips are added together to make the total score, of 106. So if the dog scores 2 on the left hip and 3 on the right hip it's total score is 5. This is often seen on a pedigree as 2/3=5 or 2-3=5. The specialists examine 9 different areas of the hip to assess the score. The lower the score the better the hip, with 0-0 being the best, and also quite rare. The GSD currently averages total scores of 19. You should as the previous poster said, look for a puppy who sire and dam is around the average or preferably lower.
This will not however ensure your puppy is free from HD. The reason for this is that HD is polygenic in nature, which means it is partly inherited aprroximately 35% -45% there are other factors which will affect the hip score of your puppy. These factors include:- over weight, underweight, over exercised, under exercised, health and illnesses. By buying from tested stock you will be reducing your risk of having an affected puppy.