There's been no hint of bribery in any of these cases yet and it doesn't fit the pattern of previous coverups in the UK which are either politically motivated like Saville or down to sheer incompetence.

The police forces in the UK are incredibly stretched so cases are often prioritised and going after a group that will inevitably result in cries of racist to protect vulnerable girls from such deprived backgrounds is not high up on that list. There is also a perceived element of 'these girls will get in trouble anyway' because of who they are and where they come from in older elements of some police forces. The distain for 'chav' culture is still very common. One girl in all this was visiting the same sexual health clinic twice a week for months to get emergency contraception and nobody there thought to question her about it.

Weirdly enough one of the actual controversial cases of bribery in all this was done by the police themselves. Northumbria police (who have been one of the more progressive forces in tackling these problems) paid a convicted sex offender £10,000 to become an informant. The information he provided seems to have resulted in the arrest and conviction of dozens of predators but the debate over the precedent has been pretty heated.

Edit: and I should add that in the last 5-10 years several forces (including Telford) have made significant strides against these issues resulting in lots of convictions. We even had a psychopath drive a car into a group of people outside a mosque because he saw a documentary on the BBC about the Rochdale case.