I think the issue here was the conduct of Operation Bobcat - they had a series of serious sex offences and started an investigation. As part of that they took DNA samples with consent from people coming to light for lesser offences (such as peeping toms) for which the law did not allow compulsory samples to be taken, including this one.
As the series of offences was believed to have stopped, the investigation sort of drifted into nothingness it seems, with the samples taken (including this one) not being progressed. They were however, stored (probably in an overcrowded station fridge full of other forgotten samples!).
When the series started up again, Operation Bobcat was reviewed and it was decided to send off all the stored samples and, Bingo!, a match was made.
In effect, therefore, the police managed to snatch defeat from the jaws of victory. If it hadn't been for their decision to take samples beyond the compulsory ones, it would not have existed. If they had either continued Operation Bobcat, or closed it down properly, the sample would have been tested. Instead they just let it drift.
In doing so they effectively allowed the suspects DNA to be retained unlawfully (i.e. in excess of his consent) and it seems there were investigative failures in relation to Operation Bobcat as it was neither continued nor properly closed down. That happens an awful lot due to individual failures of investigating officers but, more usually, simply due to pressure of work - if you get a new investigation then that is always going to take priority over tidying up a closed one and putting it away.
In reality, if Operation Bobcat had been put away properly I suspect the untested voluntary samples would / should have been destroyed without testing! So, in effect, the fuck-up actually led to the damning evidence being preserved when it shouldn't have been.
As the series of offences was believed to have stopped, the investigation sort of drifted into nothingness it seems, with the samples taken (including this one) not being progressed. They were however, stored (probably in an overcrowded station fridge full of other forgotten samples!).
When the series started up again, Operation Bobcat was reviewed and it was decided to send off all the stored samples and, Bingo!, a match was made.
In effect, therefore, the police managed to snatch defeat from the jaws of victory. If it hadn't been for their decision to take samples beyond the compulsory ones, it would not have existed. If they had either continued Operation Bobcat, or closed it down properly, the sample would have been tested. Instead they just let it drift.
In doing so they effectively allowed the suspects DNA to be retained unlawfully (i.e. in excess of his consent) and it seems there were investigative failures in relation to Operation Bobcat as it was neither continued nor properly closed down. That happens an awful lot due to individual failures of investigating officers but, more usually, simply due to pressure of work - if you get a new investigation then that is always going to take priority over tidying up a closed one and putting it away.
In reality, if Operation Bobcat had been put away properly I suspect the untested voluntary samples would / should have been destroyed without testing! So, in effect, the fuck-up actually led to the damning evidence being preserved when it shouldn't have been.

