hi ,
in response to your question , if i was in your position i would contact the person who has been given the work & ask him what are his intentions regarding the large round , hes done nothing about for the past 4-5 weeks.
if he doesnt intend cleaning it , i would then either find out the old guys details and contact him , or ask the guy whos been given the work can you have some of it & see what he says , he may want some money for the work , in which case i would ask to look at the work with him & just to make sure all the numbers of the houses are correct customers - get him to knock on the houses with you and explain the old guys packed in and you will be the new regular window cleaner.
At the end of it all , add up the total amount of money the round brings in everytime you clean it , ie= fortnighly , monthly & ask him what he would let you have the work for ?
If you need anymore advice it would be better to explain & help you over the phone ,
my number is 07788 503775 , chris
im more than willing to help you , i have 20 years experiance so know what im on about.