I had a similar case with a local transport opperator, I worked self employed driving coaches.
But because it was my only source of income and I couldnt send someone in my place I was deemed as employed.
That was 8 years ago legislation could have changed but not by that much..
If you are deemed as employed you will get all your self employed stamp payments back, and anything you paid in tax
Sherburn will be liable for the lot
Good luck...