diff --git a/include/wx/datetime.h b/include/wx/datetime.h
index e6b271c60c..8ed8dfcbda 100644
--- a/include/wx/datetime.h
+++ b/include/wx/datetime.h
@@ -306,7 +306,9 @@ public:
             return tz;
         }
 
-        long GetOffset() const { return m_offset; }
+        bool IsLocal() const { return m_offset == -1; }
+
+        long GetOffset() const;
 
     private:
         // offset for this timezone from GMT in seconds
diff --git a/interface/wx/datetime.h b/interface/wx/datetime.h
index 0f9eb55966..289ac1da48 100644
--- a/interface/wx/datetime.h
+++ b/interface/wx/datetime.h
@@ -254,6 +254,17 @@ public:
         /// Create a time zone with the given offset in seconds.
         static TimeZone Make(long offset);
 
+        /**
+            Return true if this is the local time zone.
+
+            This method can be useful for distinguishing between UTC time zone
+            and local time zone in Great Britain, which use the same offset as
+            UTC (i.e. 0), but do use DST.
+
+            @since 3.1.1
+         */
+        bool IsLocal() const;
+
         /// Return the offset of this time zone from UTC, in seconds.
         long GetOffset() const;
     };
diff --git a/src/common/datetime.cpp b/src/common/datetime.cpp
index 1fda366782..5b6013b8a8 100644
--- a/src/common/datetime.cpp
+++ b/src/common/datetime.cpp
@@ -456,9 +456,8 @@ wxDateTime::TimeZone::TimeZone(wxDateTime::TZ tz)
     switch ( tz )
     {
         case wxDateTime::Local:
-            // get the offset from C RTL: it returns the difference GMT-local
-            // while we want to have the offset _from_ GMT, hence the '-'
-            m_offset = -wxGetTimeZone();
+            // Use a special value for local time zone.
+            m_offset = -1;
             break;
 
         case wxDateTime::GMT_12:
@@ -503,6 +502,13 @@ wxDateTime::TimeZone::TimeZone(wxDateTime::TZ tz)
     }
 }
 
+long wxDateTime::TimeZone::GetOffset() const
+{
+    // get the offset from C RTL: it returns the difference GMT-local
+    // while we want to have the offset _from_ GMT, hence the '-'
+    return m_offset == -1 ? -wxGetTimeZone() : m_offset;
+}
+
 // ----------------------------------------------------------------------------
 // static functions
 // ----------------------------------------------------------------------------
@@ -1432,7 +1438,7 @@ unsigned long wxDateTime::GetAsDOS() const
 
 const tm* wxTryGetTm(tm& tmstruct, time_t t, const wxDateTime::TimeZone& tz)
 {
-    if ( tz.GetOffset() == -wxGetTimeZone() )
+    if ( tz.IsLocal() )
     {
         // we are working with local time
         return wxLocaltime_r(&t, &tmstruct);
diff --git a/tests/datetime/datetimetest.cpp b/tests/datetime/datetimetest.cpp
index fdcd9f70cb..0ae4321900 100644
--- a/tests/datetime/datetimetest.cpp
+++ b/tests/datetime/datetimetest.cpp
@@ -683,7 +683,7 @@ void DateTimeTestCase::TestTimeFormat()
 
     const long timeZonesOffsets[] =
     {
-        wxDateTime::TimeZone(wxDateTime::Local).GetOffset(),
+        -1, // This is pseudo-offset used for local time zone
 
         // Fictitious TimeZone offsets to ensure time zone formating and
         // interpretation works
@@ -1638,4 +1638,27 @@ TEST_CASE("wxDateTime::SetOnDST", "[datetime][dst]")
     }
 }
 
+// Tests random problems that used to appear in BST time zone during DST.
+// This test is disabled by default as it only passes in BST time zone, due to
+// the times hard-coded in it.
+TEST_CASE("wxDateTime-BST-bugs", "[datetime][dst][BST][.]")
+{
+    SECTION("bug-17220")
+    {
+        wxDateTime dt;
+        dt.Set(22, wxDateTime::Oct, 2015, 10, 10, 10, 10);
+        REQUIRE( dt.IsDST() );
+
+        CHECK( dt.GetTm().hour == 10 );
+        CHECK( dt.GetTm(wxDateTime::UTC).hour == 9 );
+
+        CHECK( dt.Format("%Y-%m-%d %H:%M:%S", wxDateTime::Local ) == "2015-10-22 10:10:10" );
+        CHECK( dt.Format("%Y-%m-%d %H:%M:%S", wxDateTime::UTC   ) == "2015-10-22 09:10:10" );
+
+        dt.MakeFromUTC();
+        CHECK( dt.Format("%Y-%m-%d %H:%M:%S", wxDateTime::Local ) == "2015-10-22 11:10:10" );
+        CHECK( dt.Format("%Y-%m-%d %H:%M:%S", wxDateTime::UTC   ) == "2015-10-22 10:10:10" );
+    }
+}
+
 #endif // wxUSE_DATETIME