Allow keywords starting with a variable in bdd style

atest/robot/keywords/optional_given_when_then.robot

@@ -46,6 +46,12 @@ Keyword can be used with and without prefix
     Should Be Equal    ${tc.kws[5].full_name}    Then we are in Berlin city
     Should Be Equal    ${tc.kws[6].full_name}    we are in Berlin city
 
+First word in a keyword can be an argument
+    ${tc} =    Check Test Case    ${TEST NAME}
+    Should Be Equal    ${tc.kws[0].full_name}    Given we don't drink too many beers
+    Should Be Equal    ${tc.kws[1].full_name}    Then Pekka drinks lonkero instead
+    Should Be Equal    ${tc.kws[2].full_name}    and Miikka drinks water instead
+
 Localized prefixes
     ${tc} =    Check Test Case    ${TEST NAME}
     Should Be Equal    ${tc.kws[0].full_name}    Oletetaan we don't drink too many beers

atest/testdata/keywords/optional_given_when_then.robot

@@ -48,6 +48,11 @@ Keyword can be used with and without prefix
     Then we are in Berlin city
     we are in Berlin city
 
+First word in a keyword can be an argument
+    Given we don't drink too many beers
+    Then Pekka drinks lonkero instead
+    and Miikka drinks water instead
+
 Localized prefixes
     Oletetaan we don't drink too many beers
     Kun we are in  museum  cafe
@@ -98,5 +103,9 @@ We ${x} This ${thing} Implemented
 We Go To ${somewhere}
     Should Be Equal  ${somewhere}  walking tour
 
+${person} drinks ${beverage} instead
+    Should not start with  ${person}  Then
+    Should not start with  ${person}  and
+
 Multipart prefixes didn't work with RF 6.0
     No Operation

src/robot/running/namespace.py

@@ -23,6 +23,7 @@
 from robot.output import LOGGER, Message
 from robot.utils import (eq, find_file, is_string, normalize, RecommendationFinder,
                          seq2str2)
+from robot.variables.search import search_variable
 
 from .context import EXECUTION_CONTEXTS
 from .importer import ImportCache, Importer
@@ -297,21 +298,23 @@ def _get_runner(self, name):
             runner = self._get_explicit_runner(name)
         if not runner:
             runner = self._get_implicit_runner(name)
-        if not runner:
-            runner = self._get_bdd_style_runner(name, self.languages.bdd_prefixes)
+        # handle bdd prefixes, even when swallowed by a leading variable
+        if not runner or not search_variable(runner.keyword.name).before:
+            prefix, kw_name = self._detect_bdd_prefix(name)
+            if prefix:
+                bdd_runner = self._get_runner(kw_name)
+                if bdd_runner:
+                    runner = copy.copy(bdd_runner)
+                    runner.name = f"{prefix} {kw_name}"
         return runner
 
-    def _get_bdd_style_runner(self, name, prefixes):
+    def _detect_bdd_prefix(self, name):
         parts = name.split()
         for index in range(1, len(parts)):
-            prefix = ' '.join(parts[:index]).title()
-            if prefix in prefixes:
-                runner = self._get_runner(' '.join(parts[index:]))
-                if runner:
-                    runner = copy.copy(runner)
-                    runner.name = name
-                    return runner
-        return None
+            prefix = ' '.join(parts[:index])
+            if prefix.title() in self.languages.bdd_prefixes:
+                return (prefix, ' '.join(parts[index:]))
+        return ('', name)
 
     def _get_implicit_runner(self, name):
         return (self._get_runner_from_resource_files(name) or