How do you slove a problem like.........

Maria No I mean Moss with a capital 'M'

Every year we have this very time consuming task to complete at the beginning of the summer. By now I would normally have finished but the wet weather has only served to increase the growth of the dreaded moss that looks like this!!
We have tried lots of moss killers with limited success and it takes a lot of this!!

We used to find it was only the shady areas of our back yard that were affected but it has now spread and we are talking about quite a large area to clear. This is normally a job I do but this year Embee has been helping (could be he has a certain birthday coming up and I said it had to be done before then!!) I wish I'd had someone to take a photo as we look like a couple of old crocks (clapped-out knees and hips which actually make it quite a painful task) on our kneelers scraping away. The only bit of the yard not affected seems to be the spot where my car sits as you can see from the photo. Also it's the only area to have retained some colour in the bricks. The problem seems to have got worst since we last had a professional clean a few years ago (probably coincidence)!!
So my friends any suggests sensible or otherwise to help us solve the problem??????