This is how much West Yorkshire Police spent on informants in the past five years

It paid out £451,759 to its Covert Human Intelligence Sources - commonly known as informants - in the five years from 2014/15.

Also in crime: West Yorkshire Police drug seizures at highest level in decade

The figure includes £110,249 spent in 2018/19, which was the highest expenditure by the force in any of the years examined.

It means West Yorkshire was the UK force with the seventh highest expenditure overall and for 2018/19 alone, according to data provided by 27 forces to the University of Portsmouth's journalism department.

The analysis found that police forces across the UK had spent at least £13.6m on informants over the last five years.

The highest amount paid out by any force during that period was £4.36m by the Metropolitan Police, with Police Scotland, West Midlands, Thames Valley and Northumbria rounding out the top five spenders.

Also in crime: The drugs most frequently seized by West Yorkshire Police

Former undercover policeman Neil Wood said that, in his experience, informants could be paid anything from £20 to £15,000 for information leading to successful arrests and around 90 per cent were used to investigate drug-related offences.

He is now chief executive of Law Enforcement Action Partnership, which is lobbying for drug policy reform, and has doubts about whether informants are effective in tackling drug dealing.

“If you arrest a drug dealer on the information of an informant, you remove a drug dealer," he said. “All it does is create an opportunity for another drug dealer; crime doesn’t reduce.”

But he added: “Using police informants for other crimes such as burglaries and theft is the most cost-effective form of policing you can do.”

West Yorkshire Police declined to comment when approached about its expenditure and whether the use of informants was cost-effective.

A spokesman from Taxpayers’ Alliance said: “It is critical that there is transparency in how taxpayers’ money is spent, even in the murky world of crime- fighting.

“All bodies, including the police, ought to be aware of the public interest in knowing where their cash is being spent, especially given that taxpayers are being asked to pay record amounts this year.”

Also in crime: Leeds dealer said he was 'just chilling' and had 'been to Nando's' when caught with drugs in boxers

Mark Burns-Williamson, West Yorkshire’s Police and Crime Commissioner, said: “Decisions around sensitive operational policing matters, such as the use of this tactic, are rightly for the Chief Constable. However, looking at the figures for West Yorkshire Police, which is the fourth largest force in England and Wales with a complex mix of threats and demands, the spend looks proportionate.

“We are committed to being open and transparent, however, the use of this tactic by its very nature means we are very limited in what we can discuss in public and I know that each case is considered very carefully before such decisions are made.”

How much did the force pay out each year?

2014/15 - £86,598

2015/16 - £87,710

2016/17 - £74,703

2017/18 - £92,499

2018/19 - £110,249

Total: £451,759