Q about hard landscaping and lawns

[senua]

Our garden slopes away, upwards, from the back of the house.
At the back door we have a patio, approx at the level of the house (below the DPC)..
The lawn is about 18” above this, kept in place by a retaining wall.
The wall has steps in it, from patio-height to lawn-height.
There is a path, made of stone flags, leading off from the top step.

Obviously when this was made the top-step, the path and the lawn were all at the same level.
Over time, the lawn has grown by accretion and is now slightly higher.

What is the best way to get the lawn back to its original level?

I’d probably just take the top layer off gradually rather than trying to dig loads out at once. Lawns do creep up over the years from dead grass, moss, mulch etc. If it’s only a bit higher than the path, skimming off some soil and re-seeding is usually enough. Might be worth checking drainage too so it doesn’t build up again. Might be worth doing a quick mockup in a garden planning app or software (like one of those) first, just so you can get an idea how the levels and borders will look before you start digging stuff out.

Thanks for the reply.
I think that I will try some strong scarification and see if that works.
I did go through a phase of letting grass clippings lie where they fell. It's supposed to act as a mini-mulch but I don't think it helped the quality of the soil and just created build-up instead.

You could use a handheld aerator to remove plugs of soil from the lawn in a regular pattern. The soil would then settle down slightly lower as the holes collapse in over time. That would of course leave you with a load of soil plugs to deal with, but you are going to have excess soil to deal with whatever you do.