I can only speak of the dealings I've had with them as a...

I can only speak of the dealings I've had with them as a customer, and in those instances their breakdown of charges showed statutory and employee on-costs as part of the build of their rates. I would expect back office staff are full time employees, and there would be some in parts of their operations (Thomas & Coffey springs to mind). But relaltive to the size of their total casual workforce I wouldn't see it being a torpedo, more bullet holes!