Hi Danny
This seems to be a popular question as there is another topic running regarding the same issue.
I guess the result will depend on a number of issues such as what types of addresses are being targetted (ie is it a more affluent area where more people are likely to be having their windows cleaned regularly by a window cleaner), how good is the leaflet (does it sell the benefits of you cleaning their windows), how much competition there is in the area and how aggresive are they (do you recall having leaflets through your door recently) and I dare say there are other issues to consider as well (does everyone have holidays on their mind at the moment).
If I was to stick my finger in the air and have a guess, I would think that between 1 - 2% conversion rate would be reasonable to expect.
I'm sure there are a number of members who would be very interested to know what response you do get - would you mind letting us know a few weeks after you've sent them?
Regards
Mike Boxall