Brownfingers wrote:
our garden slopes down to a park which is beyond a common access
track.


Ok...

the garden has always been wet and after a lot of rain water would
push up between concrete cracks at the bottom of the garden. This
didn't matter much.

Ok..

Last year the poplar in the park beyond died and its been fairly wet.
We now have a boggy patch in the lawn and water running down the path,
one small bed is totally waterlogged. Beyond the garden outside the
neighbours back gate the water accumulates because it cannot get
beyond a slightly raised concreted section at the back of the
neighbour two away, I doubt anything not 4x4 could now get through the
access track.
Where would you start looking for a solution, Thames water? The
Council? Some DIY work?

I have a similar problem. Essentially we have solved it by building
raised beds and also by throwing down hardcore and MOT type 1
(limestone) and covering that with the topsoil we scarped off earlier.
The 'stream' now runs UNDER the ground as it were, in the hardcore!

The key is as with any land drainage to provide a fast water path under
the land you want not to be a bog. That gets the water to where you want
it without screwing up your bit of land. General ideas include what I
described - a porous layer under the topsoil - or porous pipes
herringboned into the subsoil, or mole ploughing which is the same, but
slightly less permanent.

Its a perennial problem as more and more trees are cut down, and more an
more land is tarmacked and paved over.

Drainage beyond your property boundary is usually the local council, or
the local water authorities responsibility: However most suburban
council shave forgotten that ditches even exist, or what they are for.
The tendency is also to simply take runoff sewers as rapidly as possible
to the nearest stream or river, pass teh water downstream and make it
someone elses problem!

If the access road is private, consider raising it with MOT sub base,
and putting drainage channels down the side. If its public, try the
council. But don't hold your breath, compared with the lesbian black
disabled wheelchair drop in center, ditches don't gain many brownie
points these days. Mind you, that's a point. Cultivate a lesbian black
wheel chair user and complain that she cant get in your back gate.

They will be all over you like a rash!

Or buy a 4x4.