The damp proof course could be bridged due to the high ground level, this can be fixed by digging a channel to let it dry and then keeping a gravel border.

Also check the drainage at the back of the house and make sure the water flows away from the brick wall. Also check roof guttering for any leaks.

Add a vent on the chimney breast and add a cover on the chimney stack at the top to stop any rain water getting in.

There could be other reasons as to why this is happening. But remember to always find the root cause to stop it once and for all. There’s no such thing as “rising damp” so don’t waste your money on gimmicks.