That should have been taken into consideration, when built. But thats what i mean about high ground levels.

Over the years, people tend to add new layers of gravel/soil etc on top of the old stuff, and now the ground levels are higher than what they should be against the building.

The dpc is generally 150mm above external ground levels. External ground level, depending on floor makeup, being 150mm at least below your finished floor height.

Assuming its cavity walls due to council house,cavity going down 225mm from your dpc (depending on floor makeup), the cavity should stop anything crossing over , but again, sometimes (usually when initially built) the cavity gets filled slightly with mortar/rubbish from the brickwork above being built, and you dont have a cavity, you have a damp bridge letting water soak across.

Combine that with your garden running water towards the house, and its a potential problem. Ground might not be high though, and just the dpc work alone, possible also some drainage along the house at the bottom of the slope might fix it.

I dont know enough about the old damp courses to comment on it being worn out. I think plastic dpc started to get used in the 1970's, so its possible yours is slate or some other material.