We also bought a brush from Boots. Its called a Tangle Teaser with two bristle lengths on the same brush in soft platic. It is ideal for long haired cats and my cat loves being brushed with it. It definately works in smoothing out the undercoat to avoid knots starting up. This brush was on TV on dragons den for smoothing out tangles in human hair and was not sold for pets but
the hairdresser who designed it spent 3 years testing it out before he launched it and it definately does seem to work on cats.