Suspected Risings damp

Hi there, investigating this down pipe is the best place to start. It may be as simple as unblocking leaves from the guttering or a stone clogging the down pipe at the bottom, acting as a bung for the whole downpipe.

Yes, probably. Without looking at the outside I couldn't give an accurate answer, but check the external wall for holes/missing mortar joints, cracks on the ground near the wall, as they would allow water to ingress.

It's quite possible that the external downpipe from your neighbour's property is contributing to the rising damp issue on your external wall. When rainwater from the downpipe runs down the edge of your wall without proper drainage, it can saturate the soil around your foundation and lead to moisture wicking up through the porous materials of your wall. I would say, request your neighbour to redirect the downpipe so that it discharges into a drain or an appropriate soakaway. This will prevent water from accumulating along the base of your wall, also Ensure that the water from the downpipe is effectively channelled away from your property. If there is no nearby drain, consider installing a soakaway to allow the water to disperse into the ground without affecting your wall.

Make sure your downpipe empties into a fully clear rainwater gully because if you don't water will tend to over the years if it is left the water will end up soaking through everything w in the vicinity were it is coming out and that includes up your wall and through the masonry into your house. Also make sure gutters are clear and in full working order and like I say emptying down a fully working down pipe into a fully working rainwater gully. This should then solve your damp problems in your house.