Talk about an inflammatory headline (and yes I know it is the Daily Mail). Still, here's the original study site. In additional to asking for cats that DO and DON'T hunt, they're also asking participants in the study to change the diet of the cats. I can only assume it is to check if it affects what they hunt and how much they hunt. It is a very small number of cats though and one wonders how representative it would be.
It's also disturbing to read about the declining house sparrow population - and how there is a mention of how cats may be contributing. I recently spotted some bluebirds in my garden and from some of the reading I've been doing, house sparrows are the bane of the universe. House sparrows have been known apparently to destroy bluebird eggs and to kill adult bluebirds sitting on nests. It's interesting how in some countries they seem to proliferate (they aren't even a native bird in the US), and in others they are dying out. Also interesting are the reasons some believe that house sparrows are declining in the first place. All else being equal, cats have always been around - but our encroachment on their natural habitat is not.