Example -
35,000 new homes being built in the Ashford (Kent) area.
At 12 windows/doors per house, thats an extra 420,000 windows/doors needing cleaning every 4 to 5 weeks.
At £1 per window/door plus any conservatories, that's nearly half a million pounds up for grabs every 4 to 5 weeks.
A year down the line and there could be 35,000 gutters/facias need cleaning.
All very hypothetical I know but hopefully you get my gist.