Sports Direct founder Mike Ashley is a cartoonish villain who loves football and carries around a wad of bank notes as if he needs to be constantly reminded of the fact that he is filthy rich. He isn't trendy in the manner of a peoples' capitalist like Richard Branson, but nor does he possess the breeding and aristocratic pedigree of 'old money'. He is grasping and avaricious, but embodies the rough-around-the-edges sensibilities of someone who has qualified for billionaire status fairly recently.

This is undoubtedly a part of the reason Mike Ashley inspires such a vicious and intense level of hatred. He is of the nouveau riche that it is acceptable to despise, regardless of where you place yourself on the political spectrum.

This doesn't of course negate the fact that Sports Direct is undoubtedly a horrible company to work for. The charge sheet levelled at the company is a long one. Some workers at Sports Direct's complex in Shirebrook, Derbyshire, were paid below the minimum wage. Some were reportedly summarily dismissed for spending too long in the toilet or for taking a day off sick. All were employed on precarious zero-hours contracts. The company is, as the Business, Innovation and Skills select committee recently concluded, "founded on a business model that enables the majority of workers ... to be treated without dignity or respect".

This is all very 'Dickensian', as the overused adjective has it. Yet Mike Ashley's blimpish disregard for the niceties of running a major British company risks blinding us to the fact that nineteenth century working practices are spreading across Britain like a virulent plague. Ashley viscerally represents everything most of us hate about capitalism. Yet Sports Direct is the tip of a much bigger iceberg, and other big companies are getting away with similar work practices for no other reason than the slickness of their PR machines.

For a book I am currently writing I have recently been conducting interviews with workers at some of Britain's largest companies. The daily lives of many of these employees resembles that of the subterranean Morlocks in H.G. Wells's novel The Time Machine. A memorable quote illustrates this state of affairs succintly: "Above ground you must have the Haves, pursuing pleasure and comfort and beauty, and below ground the Have Nots, the Workers getting continually adapted to the conditions of their labour."

Whilst working undercover, I witnessed the sacking of one worker for taking too long going to the toilet.

For example, one former manager for a major British retailer that employs over 20,000 staff recently relayed to me how workers at one of the company's warehouses would sometimes be sacked for having a single day off with illness. "You were finding people, you know, good workers losing their jobs for absolutely no good reason whatsoever," he told me. "It was horrendous how they treat staff and they just laughed about it," he added.

Sweatshop conditions now abound in many UK companies iStock

Employees at another large multinational told how they were regularly underpaid, were punished for taking even a single day off sick, and saw people laid off for no apparent reason. One worker had been paid the equivalent of 45p an hour when underpayments by the employment agency were factored in. Whilst working undercover myself, I witnessed the sacking of one worker for taking too long going to the toilet.

TUC general secretary Frances O'Grady hoped to convey something of the urgency of tackling this kind of exploitation at the TUC's annual Congress this morning (September 12) in Brighton. O'Grady has told delegates that the unions will "shine a light" on "greedy business that treats its workers like animals".

Trade unions are key to pushing back against the reintroduction of workhouse-style conditions in British warehouses. Yet the law is so skewed in favour of employers that even when a trade union does get the 10% of signatures required to unionise a workplace the company often ignores it.

The growth in zero-hours contracts, for all the euphemistic language around 'flexibility', is exacerbating the problem. Almost a million people in this country now work on zero-hours contracts (or don't work, because the beauty of them for an employer is in the name: you don't have to give your staff any hours at all), and they allow bosses to turn the labour force on and off like a tap, with the resultant fear and chaos this entails for an employee's life.

Trade unions are key to pushing back against the reintroduction of workhouse-style conditions in British warehouses

A warehouse worker at one of Britain's many discount chain stores recently told me that, because all staff there were employed on zero-hours contracts, even taking a union sign-up form into work could effectively lead to your dismissal. "They'll just sack you or take away your hours for sneezing, so most people think it's not worth it."

This is why turning Mike Ashley into a uniquely evil media demon only gets you so far. Ashley may be the stereotypical fat cat: overweight, bumptious and probably, when the occasion demands it, cigar-chomping. Yet many of those I have met over the past six months are being exploited by the sort of hip, sleeves rolled up, shirt-undone-at-the-collar 'entrepreneurs' who are far more likely to be feted by British politicians than dragged up before a select committee to face the music.

'Sweatshop' used to be a pejorative term reserved for those dilapidated hangers thousands of miles away where foreign drudges toiled miserably to put cheap clothes on the high street for British consumers. Yet tucked away on the edge of an increasing number of British towns is a growing army of employees going to work in conditions which, while not of the same squalor, are of the same recognisable type as their developing world equivalents. While wealthy Britons send their money offshore, more and more of their fellow countrymen are living through the effective re-shoring of the Victorian sweatshop.