145 public authorities acquired data in 2015, and most of these requests came from the UK’s police forces and law enforcement agencies. Law enforcement officers acquired 93.7 per cent of all data requested by public authorities in 2015. Only 5.7 per cent of data was acquired by the intelligence agencies, and a mere 0.6 by public authorities such as the Financial Conduct Authority, which have the statutory ability to investigate criminal offences.

0.1 per cent of requests came from local authorities such as councils.
1,199 errors

IOCCO conducted 72 inspections in 2015, looking at approximately 15,000 randomly selected applications for communications data in detail, with a further 117,000 applications being subjected to query-based examinations; IOCCO has an internally-developed query method on the records of applications to allow the office to “identify trends, patterns and compliance issues across large volumes of applications.”
[…]
A whopping 1,199 errors were reported in 2015, a 20 per cent increase year-on-year. IOCCO reported:

The main causes for the overall rise are a larger number of incorrect identifiers being submitted by applicants on their applications or, both applications and [Single Points of Contact] acquiring data over the incorrect date or time period. Once again we highlight that a significant number of these errors relate to Internet Protocol addresses being incorrectly resolves to subscribers, which can have serious consequences.

23 of these errors were considered “serious” in 2015; nine of them caused by technical system errors and 14 were attributed to human error. The nine technical system errors resulted in “multiple consequences and a large number of erroneous disclosures (2036)” while the human errors were not dissimilar to those reported by IOCCO last year, in which a typo led to a police force raiding the wrong house.

There were 17 search warrants executed at the wrong premises in 2015, which resulted in 13 arrests, although IOCCO did not give any more details on the circumstances of those. Six of those serious consequences involved people unconnected to the investigations being “visited” by police, and on seven occasions—as happened last year—welfare checks on vulnerable people, including children, were delayed.

Joanna Cavan, the head of IOCCO who has just a few weeks left at the oversight body before joining GCHQ’s tech help desk, informed The Register that the most frequent error was caused by transposing the days and months when accommodating the American format of presenting the time.
[…]
Back in February last year IOCCO published an inquiry report [PDF] into police forces acquiring journalists’ communications data to identify and determine journalistic sources. […] IOCCO discovered it had been breached during four investigations, and in one case the commissioner, Sir Stanley Burton, determined that the conduct was serious and reckless.

Source: Brit spies and chums slurped 750k+ bits of info on you last year