Hi Ailsa
A colleague at work sugested driving in copper nails to the main shoot as they are highly toxic to the plant. I have tried this and it has some limited success.
I have also find if you cut through the ivy, at the nearest to the ground, in the main "shoots" generally within two weeks the ivy dies in most parts. This means that once the Ivy has died it is easier to remove from the brickwork without damage. This then leaves the side shoots which allow the ivy to "cling" to the wall. A wire brush can remove that reasonably easily. Good Luck
Brian