From what Ive learnt on this forum I can only make the following conclusion as to the value of this work:
46 full houses ( semis) clean 4 per hour
12 front only ( semis) clean 6 per hour
14 hours work returns £216.75 which works out at about £ 16 per hour
Average price of full semi £4.25
Average price of front only £1.50
The work frequency is too high on low paid work, if you had to do this work then personally Id rather do it every 8 weeks than every 2.
Even changing cleaning frequency to 4 weekly and adding 50% wouldnt give you the best hourly rate on your time.
Better to canvass or use canvassing company to produce work at higher hourly rate.
I dont think an existing window cleaner would want to pay to take on work like this. He would lose too many by either changing to WFP to speed up the cleaning time and or the price increases he would have to make, to get the return on his hourly rate would mean he would lose to high a percentage of the work.
Now IMO taking the above points into consideration, I would value this work at 1.5 x the monthly clean income.
IE £ 780.00
However I wouldnt want this work
Someone without the experience gained on here may see the income and the cleaning frequency and think "That looks a nice little earner for not alot of money".
Mark