diff --git a/.github/workflows/ci-tests.yml b/.github/workflows/ci-tests.yml
index ffeb139..845eb51 100644
--- a/.github/workflows/ci-tests.yml
+++ b/.github/workflows/ci-tests.yml
@@ -81,6 +81,14 @@ jobs:
           mkdir --parents ${GITHUB_WORKSPACE}/iris_test_data
           mv iris-test-data-${IRIS_TEST_DATA_VERSION} ${GITHUB_WORKSPACE}/iris_test_data_download
 
+      - name: "TEMPORARY: install specific Iris from pp-mo/lazy_encoding"
+        run: |
+          cd ${GITHUB_WORKSPACE}
+          git clone https://github.com/pp-mo/iris.git ./iris2
+          cd ./iris2
+          git checkout lazy_encoding
+          pip install -e .
+
       - name: "Run tests"
         if: matrix.session == 'tests'
         run: |
diff --git a/docs/userdocs/getting_started/introduction.rst b/docs/userdocs/getting_started/introduction.rst
index 0a4a51d..22d4e81 100644
--- a/docs/userdocs/getting_started/introduction.rst
+++ b/docs/userdocs/getting_started/introduction.rst
@@ -265,9 +265,9 @@ Example code snippets :
     Dimensions:  (dim0: 3)
     Dimensions without coordinates: dim0
     Data variables:
-        vx0      (dim0) int64 ... dask.array<chunksize=(3,), meta=numpy.ma.MaskedArray>
-        vx1      (dim0) int64 ... dask.array<chunksize=(3,), meta=numpy.ma.MaskedArray>
-        v_mag    (dim0) float64 ... dask.array<chunksize=(3,), meta=numpy.ma.MaskedArray>
+        vx0      (dim0) ... dask.array<chunksize=(3,), ...
+        vx1      (dim0) ... dask.array<chunksize=(3,), ...
+        v_mag    (dim0) ... dask.array<chunksize=(3,), ...
     Attributes:
         Conventions:  CF-1.7
 
diff --git a/lib/ncdata/dataset_like.py b/lib/ncdata/dataset_like.py
index 3702f95..4d58410 100644
--- a/lib/ncdata/dataset_like.py
+++ b/lib/ncdata/dataset_like.py
@@ -81,6 +81,11 @@ def __setattr__(self, attr, value):
         else:
             self.setncattr(attr, value)
 
+    def set_auto_chartostring(self, value):
+        if bool(value):
+            msg = "Cannot enable 'auto_chartostring' for Nc4Dataselike or Nc4VariableLike."
+            raise ValueError(msg)
+
 
 class Nc4DatasetLike(_Nc4DatalikeWithNcattrs):
     """
diff --git a/tests/data_testcase_schemas.py b/tests/data_testcase_schemas.py
index 7622da3..8212577 100644
--- a/tests/data_testcase_schemas.py
+++ b/tests/data_testcase_schemas.py
@@ -356,7 +356,7 @@ def _define_iris_testdata_testcases():
         #     "_ORCA2__votemper",
         # ]
         EXCLUDES = []
-        for filepath in _netcdf_testfile_paths:
+        for filepath in sorted(_netcdf_testfile_paths):
             param_name = str(filepath)
             # remove unwanted path elements
             param_name = param_name.replace(str(_testdirpath), "")
@@ -434,7 +434,7 @@ def _define_unit_dtype_testcases():
                     name="vx",
                     dims=["strlen"],
                     dtype="S1",
-                    data=np.array("abc", dtype="S1"),
+                    data=np.array(list("abc"), dtype="S1"),
                 )
             ],
         }
@@ -525,6 +525,7 @@ def standard_testcase(request, session_testdir):
             # """
             "small_rotPole_precipitation",
             "small_FC_167",
+            "test_monotonic_coordinate",
         ],
         # Xarray can save ~anything
         "save": [r"test_monotonic_coordinate"],
diff --git a/tests/integration/test_iris_load_and_save_equivalence.py b/tests/integration/test_iris_load_and_save_equivalence.py
index 238e456..e51252d 100644
--- a/tests/integration/test_iris_load_and_save_equivalence.py
+++ b/tests/integration/test_iris_load_and_save_equivalence.py
@@ -59,8 +59,9 @@ def test_load_direct_vs_viancdata(
         # Some of the legacy UGRID unstructured files have incorrect encodings
         # which are currently causing loading errors in Iris since UGRID loading
         # became an always-on thing in v3.11
-        "unstructured_grid__theta_nodal_xios",
-        "ugrid__21_triangle_example",
+        # TEMP - re-enable ??
+        # "unstructured_grid__theta_nodal_xios",
+        # "ugrid__21_triangle_example",
     ]
     if any(
         name_fragment in standard_testcase.name
@@ -121,7 +122,6 @@ def test_save_direct_vs_viancdata(standard_testcase, tmp_path):
         # Some of the legacy UGRID unstructured files have incorrect encodings
         # which are currently causing loading errors in Iris since UGRID loading
         # became an always-on thing in v3.11
-        "unstructured_grid__theta_nodal_xios",
         "unstructured_grid__mesh_C12",
         "ugrid__21_triangle_example",
     ]
diff --git a/tests/integration/test_iris_xarray_roundtrips.py b/tests/integration/test_iris_xarray_roundtrips.py
index d0eb2bf..3e47a3c 100644
--- a/tests/integration/test_iris_xarray_roundtrips.py
+++ b/tests/integration/test_iris_xarray_roundtrips.py
@@ -70,18 +70,24 @@ def test_roundtrip_ixi(standard_testcase, use_irislock, adjust_chunks):
         + BAD_LOADSAVE_TESTCASES["xarray"]["load"]
         # TODO: remaining unresolved problems ...
         + [
-            # string dimension problem
-            "ds__dtype__string",
             # outstanding dims-mismatch problems.
             "testing__small_theta_colpex",
+            # all-masked variables --> changing dtype, since xarray>v2026.02.0
+            "testing__cell_methods",
             # coordinate attributes on mesh coordinate variables
-            "testdata____unstructured_grid__data_C4",
             "testdata____ugrid__21_triangle_example",
-            # Problem with units on time bounds
-            "label_and_climate__small_FC_167",
             # Broken UGRID files now won't load in Iris >= 3.10
             "unstructured_grid__mesh_C12",
-            "_unstructured_grid__theta_nodal_xios",
+            # **No** mesh files will now roundtrip, since xarray 2026.04.0.
+            # This is because  xarray now normalises the array type when loading
+            # from ncdata, removing masks and converting to nanarrays (thus making ints
+            # into floats).
+            # Previously we could create xarray Datasets with masked integer variables
+            # as data -- though that was alwaysobviously a bit tricksy.
+            # Iris can't accept the new form as it insists on integer types for
+            # mesh connectivities :-(
+            # TODO: do something to get this working again?
+            "unstructured",
         ]
     )
     if any(key in standard_testcase.name for key in exclude_case_keys):
@@ -209,14 +215,15 @@ def test_roundtrip_xix(
         #   float time(time) ;
         #       time:bounds = 'time_bnds'
         #   float time_bnds(time, time_bnds) ;
-        "label_and_climate__small_FC_167",
-        "rotated__xyt__small_rotPole_precipitation",
-        # This one fails to load in xarray, for somewhat unclear reasons
-        #     NotImplementedError: Can not use auto rechunking with object dtype.
-        #     We are unable to estimate the size in bytes of object data
-        "unstructured_grid__lfric_surface_mean",
-        # Iris loses the name of the unstructured dimension, causing multiple problems
-        "unstructured_grid__data_C4",
+        # TEMP - re-enable ??
+        # "label_and_climate__small_FC_167",
+        # "rotated__xyt__small_rotPole_precipitation",
+        # # This one fails to load in xarray, for somewhat unclear reasons
+        # #     NotImplementedError: Can not use auto rechunking with object dtype.
+        # #     We are unable to estimate the size in bytes of object data
+        # "unstructured_grid__lfric_surface_mean",
+        # # Iris loses the name of the unstructured dimension, causing multiple problems
+        # "unstructured_grid__data_C4",
     ]
     if any(key in standard_testcase.name for key in excluded_casename_keys):
         pytest.skip("excluded testcase")