Gambling apps: a super casino in your pocket

It was the offer from the gambling company which he is convinced started his addiction. If he deposited up to £300, they'd match it.

James - not his real name - says: "That was basically the initial hook that got me into slot machines.

"Gambling on the internet and particularly on smartphones, using apps, you in effect have a super casino in your pocket.

"I've never actually been in a physical bookmaker's shop."

In three months, James went from gambling a hundred pounds a month to five thousand pounds in a day. When he finally stopped, he was 80 thousand pounds in debt.

"For a time it ruined my life - up until the point that I was seriously considering suicide. Basically, I had ruined myself financially"

James wanted to understand his relationship with the gambling companies, in particular Sky Bet - and the trail of personal data he had agreed to share with them when he signed up. He issued what's known as a Data Subject Access Request.

But to start to get the full picture, he had to find out his unique code and put in requests not just to Sky Bet, but also to three data harvesting companies which SkyBet sends data to from its data warehouse: Signal, which profiled his behaviour for marketing - not just from Sky Bet but other companies too; Iovation, which monitored what device he was using, when and how often; and TransUnion, the credit reference company which owns the other two firms.

The subject access request from Iovation showed almost 19,000 separate items of data, tracking his Sky Bet gambling. Sky Bet says it uses this for fraud prevention.

The behavioural profiling by Signal which can be used for marketing has more than 85 categories, and James found it had 166 fields of data on him, not just from Sky Bet. To take just three of the categories profiled: it categorises him as a high-value customer; it knows he chases losses; and it knows the percentage of its emails he opens.

TransUnion, the data and insights company, told the BBC it offers "various services to gaming operators to support responsible conduct and protect the vulnerable from exploitation."

"These include confirming age and identity, preventing fraud and checking affordability... All our relationships comply with relevant legal and regulatory frameworks."

Sky Bet said it uses "a number of third party data providers" for fraud detection, age verification and marketing.

"The data that was provided to the customer in this case upon request came from several third parties and includes information that Sky Betting & Gaming does not have access to," it added.

Ravi Naik, from the law firm AWO, helped James access his files. He says we need to understand what information we give away: "Gambling companies do not operate in a silo of data - they operate in this wider ecosystem. There's data flowing in different times and in different ways.

"The concern for our clients is that their data is being used for behavioural surveillance, understanding what you are doing, who you are and what you like."

The Gambling Act 2005 became law across Great Britain in September 2007 - and now the government is reviewing it to make it fit for the digital age. The call for evidence ends at the end of March. Northern Ireland is regulated separately.

Since the law was introduced, the online gambling industry has exploded, taking in around £6bn a year.

The review of the Gambling Act will look at whether the law is effective and gives the right protections - something the regulator - the Gambling Commission - says it welcomes.

Gambling today has shifted online. It's part of the attention economy: the war for our attention that has made a small group of (mostly Californian) companies the richest in human history.

To a much greater extent than is generally acknowledged, the price of the free and open web that we have today is paid in privacy. Our every click, open and scroll is a signal that creates an item of data. Algorithms then sift and sort that data to build very detailed profiles of us, which in turn allows us to be targeted.

Often it is advertisers who target us. This is the means by which Google and Facebook have become very rich.

With good reason, there has been a big focus in recent years on those institutions who together comprise Big Tech. But the harvesting of our data trails is something that a bewilderingly vast assortment of companies specialise in - including gambling companies.

It's only when you try to find out what these companies know about you - as 'James' did - that you discover how much of yourself you've handed over.