Thousands have their lives under threat each year

Len Gridley, a vocal opponent of the Dale Farm travellers' site, who received a "threat to life" warning notice after a death threat was made against him.

An investigation by the Press Association found at least 1,948 “threat to life” notices have been issued by police forces across the UK, telling people their lives were in danger, since 2012.

Men and women aged 17 to 74 were among those to receive the so-called “Osman warning” letters, according to figures from 27 forces, which were released under the Freedom of Information Act.

The total number of warnings is likely to be much higher as police in West Midlands, Merseyside and Greater Manchester - which has been investigating shootings potentially linked to the death of gangland “Mr Big” Paul Massey - were among the forces which refused to provide figures.

South Yorkshire Police said 34 Osman warnings were issued in 2014, compared with 19 in 2013 and 16 in 2012. They included three Osman warnings issued to women in 2014, two in 2013 and one in 2012.

North Yorkshire Police said one Osman warning was issued last year, compared with seven in 2013 and 14 in 2012. The force did not disclose how many warnings were issued this year. A spokeswoman said: “If a criminal suspects someone has been given an Osman warning then they will become aware that there is intelligence available and this could therefore place that individual at risk.”

Humberside Police refused to reveal the number of Osman warnings issued because it would cost too much to retrieve the figures.

Instead, the force revealed the number of “threat-to-life assessments” which identify when there is a “real, credible and immediate threat to life or to seriously harm”. Humberside Police said 116 threat-to-life assessments were recorded last year, compared with 116 in 2013 and 173 in 2012. West Yorkshire Police refuse to answer.

The National Police Chiefs’ Council (NPCC) said Osman warnings had proven “highly effective” in helping to protect people “in the overwhelming majority of cases”.

Len Gridley, a vocal opponent of the Dale Farm travellers’ site, said he received a “threat to life” warning notice after a death threat was made against him.