when you get used to this way of working, it can work, but don't expect 2 people to bring in double what one can. Our guys average between £10 and £15 per hour, but that is made up of hourly rate and bonuses and they have to achieve a target figure to get the top rates. If you gave your mate 50% of the takings, for easiness say overall £200, so you gave him £100, on top of that you have to fork out for Employers National Insurance, Employees P & L Insurance, Holiday pay, and general overheads!
If you do this you are probably taking only in the region of 30% yourself of the £200. We work on that if all overheads and staff costs comes to on average 56% then we get 44% for the privilege of employing them. That's us though and obviously others do it differently!