Gotta be firm here. I'm going to try the following:

1. Ignore everything posted by Iains and Keith.

2. If possible, post something relevant to the thread after they've posted but without referring to any points they make.

3. Do not refer to them by name.

4. Don't make points that may appear to be responses to something they've said.

In short, cut them dead. Completely. They get what they want not by making constructive arguments but by provoking. As soon as we respond they win. They're both sick in the head. So let's try harder, eh?

Starting... NOW! :-)