diff --git a/src/wily/archivers/git.py b/src/wily/archivers/git.py
index 71e8b802..dedeed27 100644
--- a/src/wily/archivers/git.py
+++ b/src/wily/archivers/git.py
@@ -4,6 +4,7 @@
 Implementation of the archiver API for the gitpython module.
 """
 import logging
+from pathlib import Path
 from typing import Any, Dict, List, Tuple
 
 import git.exc
@@ -195,3 +196,32 @@ def find(self, search: str) -> Revision:
             modified_files=modified_files,
             deleted_files=deleted_files,
         )
+
+    def is_data_outdated(self, filename: str, key: str) -> bool:
+        """
+        Check whether file contents match between revision and working directory.
+
+        :param filename: The name of the file to check.
+        :param key: The revision to which compare file contents.
+        :return: Whether the working directory copy of the file is outdated.
+        """
+        commit = self.repo.rev_parse(key)
+        filepath = str(Path(self.repo.working_dir) / filename)
+        diff = commit.diff(None, filepath)
+        return bool(diff and diff[0].change_type == "M")
+
+    def get_file_contents(self, rev_key: str, filename: str) -> str:
+        """
+        Get contents of a file in a given git revision.
+
+        :param rev_key: The key for the revision at which to fetch the file.
+        :param filename: The name of the file for which to get the contents.
+        :return: The file contents.
+        """
+        git_filename = filename.replace("\\", "/")
+        contents = self.repo.git.execute(
+            ["git", "show", f"{rev_key}:{git_filename}"],
+            as_process=False,
+            stdout_as_string=True,
+        )
+        return str(contents)
diff --git a/test/integration/test_archiver.py b/test/integration/test_archiver.py
index 693c5a72..8c300bc2 100644
--- a/test/integration/test_archiver.py
+++ b/test/integration/test_archiver.py
@@ -1,6 +1,7 @@
 import pathlib
 
 import pytest
+from git.exc import GitCommandError
 from git.repo.base import Repo
 from git.util import Actor
 
@@ -64,6 +65,24 @@ def test_git_end_to_end(tmpdir):
 
     assert (tmppath / "test.py").exists()
 
+    # Test that outdated file contents are detected
+    archiver2 = GitArchiver(config)
+    outdated = archiver2.is_data_outdated("test.py", "HEAD")
+    assert not outdated
+    with open(tmppath / "test.py", "w") as file2:
+        file2.write("print(2)")
+    outdated = archiver2.is_data_outdated("test.py", "HEAD")
+    assert outdated
+
+    # Test that file contents can be fetched for different revisions
+    content = archiver2.get_file_contents("HEAD", "test.py")
+    assert content == "print(1)"
+    with pytest.raises(GitCommandError):
+        # Error if file is not known in revision
+        content = archiver2.get_file_contents("HEAD~1", "test.py")
+    content = archiver2.get_file_contents("HEAD~1", ".gitignore")
+    assert content == ".wily/"
+
 
 def test_dirty_git(tmpdir):
     """Check that repository fails to initialise if unchecked files are in the repo"""