I think Sean and Gordon have a little mis communication going on here. When pricing a job it will always come down to how long you think it will take, you cant just throw out a number. But, when quoting you give a final price, not "I will charge you this much per hour". Then it is up to you to meet or exceed your initial expectations. I have quoted jobs at 15 pounds per hour from my extimate but it has taken me half the estimated time so in reality I made 30 pounds per hour. I always try to leave my self some breathing space in my quotes in case I did miss something, but so far knock on wood, I have always met of beat my initial estimate. The question is 20 pounds per hour too much can get a different answer from many people. Are you adding chemicals, equipment, and travel costs on top of that or are they included in the cost. I know I am stating the obvious but a place with a marble floor costs a lot more to clean than a carpeted floor, not only for the specialised labour but for the chemicals and equipment needed. Basically, I think Sean and Gordon are on the same track just explaining it different.
Cheers
Gilbert