Employed or self-employed?
In order to answer this question it is necessary to determine whether the person works under a contract of service (employees) or under a contract for services (self-employed, independent contractor). For tax and NICs purposes, there is no statutory definition of a contract of service or of a contract for services. What the parties call their relationship, or what they consider it to be, is not conclusive. It is the reality of the relationship that matters.

In order to determine the nature of a contract, it is necessary to apply common law principles. The courts have, over the years, laid down some factors and tests that are relevant, which is included in the overview below.

As a general guide as to whether a worker is an employee or self-employed; if the answer is 'Yes' to all of the following questions, then the worker is probably an employee:

Do they have to do the work themselves?
Can someone tell them at any time what to do, where to carry out the work or when and how to do it?
Can they work a set amount of hours?
Can someone move them from task to task?
Are they paid by the hour, week, or month?
Can they get overtime pay or bonus payment?
If the answer is 'Yes' to all of the following questions, it will usually mean that the worker is self-employed:

Can they hire someone to do the work or engage helpers at their own expense?
Do they risk their own money?
Do they provide the main items of equipment they need to do their job, not just the small tools that many employees provide for themselves?
Do they agree to do a job for a fixed price regardless of how long the job may take?
Can they decide what work to do, how and when to do the work and where to provide the services?
Do they regularly work for a number of different people?
Do they have to correct unsatisfactory work in their own time and at their own expense?

I know a guy who had van drivers working the same way and signing the declaration "i realise i am liable for my own NI and tax payments"

The taxman hit him with a £100K tax bill, he had to sell the business to pay the taxman or risk losing his house....

bit if the van drivers signed the declaration and didnt pay any tax why is that the business owners problem?

If the answer is 'Yes' to all of the following questions, it will usually mean that the worker is self-employed:

Can they hire someone to do the work or engage helpers at their own expense?
No

Do they risk their own money?
Yes

Do they provide the main items of equipment they need to do their job, not just the small tools that many employees provide for themselves?
Sometimes

Do they agree to do a job for a fixed price regardless of how long the job may take?
Not too sure about this one. If there is waiting time etc we charge extra for that but the driver doesn't set the rate they are to be paid

Can they decide what work to do, how and when to do the work and where to provide the services?
Usually, but, one of the companies here will disable your data head if you refuse to do a job

Do they regularly work for a number of different people?
No

Do they have to correct unsatisfactory work in their own time and at their own expense?
No because the contract is not with the driver but the operator so I believe it would be the operators responsibility to pay out any monies and then try and get it from the driver

they get a third of the takings

If you have to answer yes to all these questions then I would wonder how any ph driver is self employed

i am, i own the car, invoice my own work, place the tender bids and wash the car