Just been surfing, and found this window cleaning round for sale.
http://www.sheffieldforum.co.uk/archive/index.php/t-42092.html£700 per month is not bad, but seems like an awful lot of work to get it!
If he does these twice a month then, they are obviously not going to take long to do, but to complete 180 house in 7 days, he has to clean 25+ per day, earning around £50! Me thinks they must be small houses, but £2 a house??