simon,
we have been using gardiner poles and the one problem we have found with them (something that alex gardiner mentioned in a post the other day) is, if, as we do, you use a 12' pole to do the upstairs windows and then shorten it to do the groundfloor windows then the pole does wear quite a lot at the point where you lock it off to do the groundfloor, this means that after a while, maybe a week or so the bit of the pole with the brush on, starts to slip round, ie it wont lock into place....hope i am explaining this right....so you lock off with the pole out a bit further, this is fine for a while, but then the same problem occurs, eventually you are trying to the groundfloor windows witha pole thats about 9' long.
alex says that he avoids this by usinng a shorter 4' pole for groundfloor, but as far as we can see this would mean carrying 2 poles around, maybe over rooves etc, not very practical methinks