What kind of firms are taking over the NHS under the coalition's privatisation plans?

I've looked at the books and found that a firm that doesn't pay any tax towards the NHS is getting work from the NHS.

NSL - "intelligent outsourcing" - is winning multimillion-pound contracts to take over ambulance services throughout Britain.

But I checked back through the last six years of their accounts and found NSL didn't pay corporation tax in any of them.

We are all paying tax to keep the NHS going, but NSL is just taking cash out without giving any back.

The firm is doing very well. Its current annual report boasts of "another year of strong operational and financial results" and "strong growth."

It says its "financial key performance indicators" include an "operating profit" of £9.9 million.

But it didn't give anything to the taxman. In fact, NSL says it has a "tax credit" of £1.2m - that the taxman owes them that much money.

NSL manages this thanks to the private equity trick.

The firm is owned by private equity company AAC Partners.

It has loaded NSL so heavily with debt that the entire firm's revenue flows out in interest payments before it reaches the taxman.

In the latest year NSL paid £13m interest, much of it to companies in the same group.

So cash flows out of AAC Partners-owned NSL to AAC Partners and their friends and the operating profit is transformed into an overall £3m loss.

NSL says in its annual report that the firm encourages all its employees to "give something back to their local community."

The firm says it is "encouraging and supporting all local charitable efforts."

It even gives some company cash to the NSPCC.

But it won't give anything to the tax-man - even though the business would not exist without taxpayer support.

Maybe with all that money it saves not paying taxes, NSL can afford to offer a pretty swish ambulance service.

It says it can. The firm's annual report opens with a David Brentish claim that "NSL's vision is to be the number-one provider wherever we deliver services."

But actually search "NSL" on the news databases and you get a litany of complaints.

In March East Midlands Ambulance Service issued an apology for poor service in non-urgent ambulance services in Derbyshire.

It said it was "working urgently" with a new provider - NSL - to make things better after patients missed appointments.

NSL blamed "the volume of calls initially exceeding our planning assumptions, which resulted in difficulty making contact for bookings and queries very difficult."

This month the Kent Messenger reported: "A wheelchair-bound pensioner with incurable cancer nearly missed a seven-hour chemotherapy session after his hospital transport failed to turn up."

The patient's wife was repeatedly told an ambulance "was on its way."

She said: "We feel we were lied to all that time. We eventually learned from the switchboard that they had crew problems."

The newspaper says this is just "the latest incident in a string of delays experienced by people since private firm NSL Care Services took over running patient transport services under a £26m contract."

The NHS Commissioning Group said it would raise these problems "in the strongest possible way."

In North Staffordshire NSL is laying off 35 ambulance drivers after winning a £3m contract to run ambulances in the area.

Before NSL took over the drivers were told they were safe, but after the West Midlands Ambulance Trust signed the contract NSL announced that a third of the 120 staff would be made redundant.

At least you hope the firm knows what it's doing.

Most people hope ambulances are run by people interested in medicine - by the NHS, in fact.

But NSL is really a car parking firm. It's a breakaway unit of National Car Parks.

According to the firm's accounts NSL's highest paid director gets £475,000 a year. This is probably its managing director Mark Underwood.

He used to work for private prison firm Geo, running private jails in Australia, South Africa and Britain.

So the NHS is being taken over by a car park firm run by a prison boss. And there's more.

NSL moved into the NHS by taking over a small ambulance firm in 2010, shortly after Cameron's election sped up NHS privatisation.

NSL's biggest business is supplying councils with traffic wardens.

Last January NSL traffic warden Hakim Berkani won an employment tribunal hearing after he was sacked by the firm.

Berkani refused to meet NSL's secret minimum ticket quotas. He preferred to warn motorists they were wrongly parked than follow NSL's targets and act in a "predatory and sometimes dishonest" way.

NSL didn't like that.

So this firm that doesn't pay tax is taking money from taxpayers in a range of sectors - and all to run cheap, target-driven public services.

Follow Solomon Hughes on Twitter @Sol_Hughes_Writer.