We have a 19th C house with mould that effects only on one side of the house. Brick work seems pourous. Insulation problem?

Without seeing the problem its hard to call. Certainly no water should be directed towards any building and if that is nessasary then i would expect to see a linear drain in front of the property to catch rainwater. But there could be a few reasons why one side is damp, possible damp course failure? Height of ground more than 150mm below damp course? Leaking down pipe from gutter? Overflow pipe leaking? Roof leaking? Damaged guttering? Leaking bathroom pipework... The list is pretty large. Your next step is to invite estimates from mybuilder.com and get a professional view from a local tradesman.

The ground should be minimum 150mm below your dpc/and finish floor level. Your neighbours drive shouldnt be running to your outside wall. You might have to fit some atco drainage channels.