Sounds like either a mole or vole. They are mouse like rodents that cause subterranean damage. A vole will gnaw at the base of a tree or shrub, especially in winter. A vole may also damage flower bulbs and potatoes in the garden. But mainly, the vole will eat the stems and blades of lawn grass. Moles are carnivorous. Wasps can take up residency in the trenches left behind.

They must be mini voles or moles then, Bathgate - 25mm is only about an inch wide. Might be a tiny mouse, seems a bit too large for ground bees, their holes are usually about half an inch.

A mole would leave other damage on the lawn surely - the only mole holes I've seen have been in the centre of a molehill.

We have a family of blackbirds who spend ages digging holes in our lawn, inches away from us, and pulling out tasty worms and grubs. We thought it was a fox until we saw it for our own eyes.

We have loads of small holes in our 'lawn' which I have always put down to mice or voles. The Field voles are very small being 9-11cm long plus the tail. Could also be Common or Pygmy shrews, though not sure that they live in holes! Common shrew 5-8cm, pygmy 4-6cm, plus tails. Because we are on heavy clay the ground tends to crack leaving inviting slits in the ground for small mammals. Not sure how long they will all last now that I have seen a stoat about!