diff --git a/definitions/grib2/localConcepts/s2s/MTG2SwitchConcept.def b/definitions/grib2/localConcepts/s2s/MTG2SwitchConcept.def
new file mode 100644
index 000000000..4813ddbef
--- /dev/null
+++ b/definitions/grib2/localConcepts/s2s/MTG2SwitchConcept.def
@@ -0,0 +1,2 @@
+# This pseudocentre should remain permanently on pre-MTG2 definitions
+0 = {edition=2;}
\ No newline at end of file
diff --git a/definitions/grib2/localConcepts/tigge/MTG2SwitchConcept.def b/definitions/grib2/localConcepts/tigge/MTG2SwitchConcept.def
new file mode 100644
index 000000000..4813ddbef
--- /dev/null
+++ b/definitions/grib2/localConcepts/tigge/MTG2SwitchConcept.def
@@ -0,0 +1,2 @@
+# This pseudocentre should remain permanently on pre-MTG2 definitions
+0 = {edition=2;}
\ No newline at end of file
diff --git a/definitions/grib2/localConcepts/uerra/MTG2SwitchConcept.def b/definitions/grib2/localConcepts/uerra/MTG2SwitchConcept.def
new file mode 100644
index 000000000..4813ddbef
--- /dev/null
+++ b/definitions/grib2/localConcepts/uerra/MTG2SwitchConcept.def
@@ -0,0 +1,2 @@
+# This pseudocentre should remain permanently on pre-MTG2 definitions
+0 = {edition=2;}
\ No newline at end of file
diff --git a/definitions/grib2/products_crra.def b/definitions/grib2/products_crra.def
index ebf328a6f..c7708aa05 100644
--- a/definitions/grib2/products_crra.def
+++ b/definitions/grib2/products_crra.def
@@ -142,10 +142,11 @@ if (marsStream is "dame") {
   unalias mars.step;
 }
 # MTG2 support given lack of local section
-if (tablesVersion <= tablesVersionMTG2Switch) {
-    # Pre-MTG2
-    constant MTG2SwitchDefault = 0;
-} else {
-    # All other cases we are post-MTG2
-    constant MTG2SwitchDefault = 1;
-}
+# This comes after the paramId is already decided, so doesn't work.
+# if (tablesVersion <= tablesVersionMTG2Switch) {
+#     # Pre-MTG2
+#     constant MTG2SwitchDefault = 0;
+# } else {
+#     # All other cases we are post-MTG2
+#     constant MTG2SwitchDefault = 1;
+# }
diff --git a/definitions/grib2/products_s2s.def b/definitions/grib2/products_s2s.def
index 3525c0db3..01fbda3ed 100644
--- a/definitions/grib2/products_s2s.def
+++ b/definitions/grib2/products_s2s.def
@@ -111,10 +111,11 @@ if (is_ocean3d_param) {
 }
 
 # MTG2 support given lack of local section
-if (tablesVersion <= tablesVersionMTG2Switch) {
-    # Pre-MTG2
-    constant MTG2SwitchDefault = 0;
-} else {
-    # All other cases we are post-MTG2
-    constant MTG2SwitchDefault = 1;
-}
+# This comes after the paramId is already decided, so doesn't work.
+# if (tablesVersion <= tablesVersionMTG2Switch) {
+#     # Pre-MTG2
+#     constant MTG2SwitchDefault = 0;
+# } else {
+#     # All other cases we are post-MTG2
+#     constant MTG2SwitchDefault = 1;
+# }
diff --git a/definitions/grib2/products_tigge.def b/definitions/grib2/products_tigge.def
index c3c9a0b4b..00dcce6df 100644
--- a/definitions/grib2/products_tigge.def
+++ b/definitions/grib2/products_tigge.def
@@ -83,10 +83,11 @@ alias mars.stream = marsStream;
 alias mars.type   = marsType;
 
 # MTG2 support given lack of local section
-if (tablesVersion <= tablesVersionMTG2Switch) {
-    # Pre-MTG2
-    constant MTG2SwitchDefault = 0;
-} else {
-    # All other cases we are post-MTG2
-    constant MTG2SwitchDefault = 1;
-}
+# This comes after the paramId is already decided, so doesn't work.
+# if (tablesVersion <= tablesVersionMTG2Switch) {
+#     # Pre-MTG2
+#     constant MTG2SwitchDefault = 0;
+# } else {
+#     # All other cases we are post-MTG2
+#     constant MTG2SwitchDefault = 1;
+# }
diff --git a/definitions/grib2/products_uerra.def b/definitions/grib2/products_uerra.def
index 5dbbd09df..f05eb2737 100644
--- a/definitions/grib2/products_uerra.def
+++ b/definitions/grib2/products_uerra.def
@@ -98,10 +98,11 @@ alias mars.stream = marsStream;
 alias mars.type   = marsType;
 
 # MTG2 support given lack of local section
-if (tablesVersion <= tablesVersionMTG2Switch) {
-    # Pre-MTG2
-    constant MTG2SwitchDefault = 0;
-} else {
-    # All other cases we are post-MTG2
-    constant MTG2SwitchDefault = 1;
-}
+# This comes after the paramId is already decided, so doesn't work.
+# if (tablesVersion <= tablesVersionMTG2Switch) {
+#     # Pre-MTG2
+#     constant MTG2SwitchDefault = 0;
+# } else {
+#     # All other cases we are post-MTG2
+#     constant MTG2SwitchDefault = 1;
+# }
diff --git a/src/accessor/grib_accessor_class_g2_concept_dir.cc b/src/accessor/grib_accessor_class_g2_concept_dir.cc
index acf46afae..848c9a4c8 100644
--- a/src/accessor/grib_accessor_class_g2_concept_dir.cc
+++ b/src/accessor/grib_accessor_class_g2_concept_dir.cc
@@ -55,8 +55,18 @@ int grib_accessor_g2_concept_dir_t::unpack_string(char* v, size_t* len)
     if (err) return err;
 
     size = sizeof(datasetForLocal);
+    bool datasetForLocalExists = true;
     err = grib_get_string(h, datasetForLocal_, datasetForLocal, &size);
-    if (err) return err;
+    if (err) {
+        if (err == GRIB_NOT_FOUND) {
+            // This can happen if accessor is called before section 4
+            datasetForLocalExists = false;
+            err = 0;
+        }
+        else {
+            return err;
+        }
+    }
 
     const size_t dsize = string_length() - 1; // size for destination string "v"
     if (preferLocal) {
@@ -74,8 +84,8 @@ int grib_accessor_g2_concept_dir_t::unpack_string(char* v, size_t* len)
         }
     }
 
-    // Override if datasetForLocal is not unknown
-    if (!STR_EQUAL(datasetForLocal, "unknown")) {
+    // Override if datasetForLocal exists and is not unknown
+    if (datasetForLocalExists && !STR_EQUAL(datasetForLocal, "unknown")) {
         if (mode_ == 1) {
             snprintf(v, dsize, "%s", masterDir); // conceptsDir1
         } else {
@@ -83,17 +93,6 @@ int grib_accessor_g2_concept_dir_t::unpack_string(char* v, size_t* len)
         }
     }
 
-    // if (mode_ == 1) {
-    //     if (STR_EQUAL(datasetForLocal, "unknown")) {
-    //         char centre[64] = {0,};
-    //         size = sizeof(centre) / sizeof(*centre);
-    //         grib_get_string(h, "centre", centre, &size);
-    //         snprintf(v, 256, "grib2/localConcepts/%s", centre);
-    //     } else {
-    //         snprintf(v, 64, "grib2");
-    //     }
-    // }
-
     size = strlen(v);
     ECCODES_ASSERT(size > 0);
     *len = size + 1;