Private investigators were used by councils across the region but Bradford-based investigator Yin Johnson said many authorities also had services in house, which may suggest the employment of such methods was far higher.
A freedom of information request sent to all Yorkshire councils by the Yorkshire Post revealed that between 2016 and September 2020, at least £317,072.25 was spent on private investigators.
In 2016, the total figure was £55,380.20, rising to £68,335.39 in 2017, £68,649.27 in 2018, and £75,823.20 in 2019.
For the partial period of 2020, £48,884.19 had been spent.
And the Taxpayers’ Alliance said: "Taxpayers will be concerned that Yorkshire councils are spending large sums playing Poirot."
Sheffield and Kirklees councils were the highest spenders, putting £196,709 and £104,028.46 towards these costs over the full period respectively.
Sheffield City Council was unable to confirm for what reasons private investigators were used, but at Kirklees “contractors are primarily used for effecting service of court papers on defendants and other parties”.
The council said this can involve “making enquiries to establish the whereabouts of an individual” but added: “These contractors are not generally used for other investigations, or for conducting covert surveillance.”
And a spokesman said: “Whilst we cannot comment on other authorities, it is likely that they will have similar costs for this type of work. However, due to their supplier being known by a different name locally, they may not have not included them in their response.”
Councils in Leeds, Barnsley, Harrogate, and Ryedale had also used private investigators, while all other councils either did not respond or had no recorded payments for such services over the almost five years.
In Harrogate, £7,000 was spent in 2018 when “an investigation was required in relation to a serious complaint received”.
In Leeds, £6,709.79 was spent over the course of the time period, but no further information could be given due to child protection.
While in Barnsley, £1,925 was spent in 2019 for “validation of a claimant’s injuries in connection with an insurance claim”.
Just £700 was used in Ryedale in 2016 to serve an enforcement notice abroad.
Jeremy Hutton, policy analyst at the TaxPayers' Alliance said: "There may be circumstances where it is appropriate to hire private investigators. But it seems to have become the norm for some councils.
"Local authorities should not pay over the odds for external investigators, especially for tasks that could potentially be fulfilled in-house."
But Mrs Johnson, who has run JJ Associates International with her husband Phil since 1987, said that for many councils, using in-house legal services was the usual way of operating - and that taking advantage of the skills of PIs often saved authorities money in the long run.
She said: “In my experience they have somebody in the office go out and do an investigation, and then they've called upon someone like me to comment.”
But she had worked with councils in the past, as well as Government bodies, and said one example of use of an investigator would be when travellers moved on to council land.
“It's a commercial thing, because it's commercial property. And if travellers come, say, on to a car park in the middle of Leeds, the council then decides ‘we need to remove these people, they shouldn't be there, they're trespassing’,” she said.
“So then, it's a very old law, we have to serve the piece of land to get rid of whoever's come onto there illegally, so court papers are then issued.
“And we have to go about it in a very old fashioned manner, you would think that we'd have to go and contact the people themselves, but it's actually the land and that involves placing three sticks of wood or various parts of the land.”
She said she had also in the past been employed by councils in North Yorkshire to serve eviction notices if tenants had not paid their rent.
“We’ve done different things to do with council workers that have come through an external law firm, where we've done the surveillance on particular targets and that's been paying sickness benefits to a person, and the council's been informed that this person is not actually sick, for example somebody has got a bad back and some work colleague has seen them at the sports hall in work time playing squash or sitting at the riverbank fishing,” she said.
“And at the end of the day it’s a lot of money on salary if they're claiming from day one to their retirement, that can go into the hundreds of thousands.”
She added: “The councils are paying out on a particular job a smaller fee, it might only be one per cent of the potential amount, and it's the same with the insurance companies.
“We used to work for HMRC, that was related to taxes, and it can be a massive amount of money that they're trying to claim.”
Other councils were contacted for comment.