Ann: Half Yearly Report and Accounts , page-28

Puzzled,
I agree that the 10% figure is a generalisation based on the TST which will cross react with BCG so the actual conversion rate will be higher (as is starting to be seen in the work by Diel, etc) but even if this doubles so that 20% convert to active disease at some time in their life the studies would still have to be very big and take a long time to see a statistically significant difference in the conversion rates between QFT and the TST.
But this is the sort of evidence that the medics say they need before moving totally to QFT for all screening (healthcare workers, workers and residents in institutions such as prisons and care homes, contact tracing, organ transplant recipients, new entrant from high TB endemic countries...).
The market is huge which is probably one reason why many medics hide behind the lack of concrete evidence of superiority of the QFT (more studies like the one I describe above). They are frightened that if they admit the QFT is superior the cost of funding the QFT in all these areas will be huge.