On Feb 4, 5:50 pm, "Robbo" wrote:

If you're on a clay subsoil with loads of builders debris and crap in the
ground no amount of additional drainage within a reasonable cost is going to
alleviate the problem.

I agree, the only real way is to replace the boggy stuff with a more
stable substance. Even a few inches will help but it mustbe able to
drain away which it would by the sound of it as you have a slope and
you're higher than neighbouring properties.

If you fill holes with gravel you'll end up with wet gravel filled
holes.