I would think there are lots of jobs, like cafe staff, supermarket staff, etc, where there may be some equally qualified people who apply. In any case of equally qualified people, I think the best solution may be to choose at random and keep the other person(s) on file in case the first one chosen doesn't last. Perhaps that should be put into law.
I suppose my question would be: Could a person claim negative discrimination if they fail to get a job where the other applicant got the job because of positive discrimination?
Oh, and on the article's point of positive discrimination not having a precedent in UK law: Northern Ireland is probably slightly different, but there were the Patten recommendations that were carried out by the Police Service of Northern Ireland. People from a protestant background weren't told they couldn't join, but the training college places had a quota for each year of 50/50 protestant/Catholic. After the quota for each background was filled, further applicants of that background had to wait a year. Because there were fewer applicants from a Catholic background they would be much less likely of oversubscribing their quota.