He'll be £15hr or more in (red)diesel and tyre wear alone. Take £15hr for himself as a wage you're already at £30.Where costs are at now I don't think any job that involves turning the key of a 120hp+ tractor is worth doing for less than £50/hour. Be better off going to the pub than run that outfit for £30/hour
Depreciation/maintenence will be £10-15hr so that £45 without even talking about profit.
Couple of small repairs on the tractor or a full service and you are over a grand instantly. Only time £30hr works is if you helping a mate out then they help you out another time.
£50hr sounds a lot when your paying someone that for days but with the costs involved nowadays it kind of has to be