diff --git a/qt/applications/workbench/workbench/plugins/workspacewidget.py b/qt/applications/workbench/workbench/plugins/workspacewidget.py
index fc77a3bfe493c8021ba03cd55e34e2476f0fdc48..9d04a439f1700311e19f8f7110b7fc1865aede73 100644
--- a/qt/applications/workbench/workbench/plugins/workspacewidget.py
+++ b/qt/applications/workbench/workbench/plugins/workspacewidget.py
@@ -22,7 +22,6 @@ import functools
 # third-party library imports
 from mantid.api import AnalysisDataService, MatrixWorkspace, WorkspaceGroup
 from mantid.kernel import Logger
-from mantidqt.widgets.workspacewidget.mantidtreemodel import MantidTreeModel
 from mantidqt.widgets.workspacewidget.plotselectiondialog import get_plot_selection
 from mantidqt.widgets.workspacewidget.workspacetreewidget import WorkspaceTreeWidget
 from qtpy.QtWidgets import QVBoxLayout
@@ -72,18 +71,17 @@ class WorkspaceWidget(PluginWidget):
         super(WorkspaceWidget, self).__init__(parent)
 
         # layout
-        workspacewidget = WorkspaceTreeWidget(MantidTreeModel())
-        self.workspacewidget = workspacewidget
+        self.workspacewidget = WorkspaceTreeWidget()
         layout = QVBoxLayout()
         layout.addWidget(self.workspacewidget)
         self.setLayout(layout)
 
         # behaviour
-        workspacewidget.plotSpectrumClicked.connect(functools.partial(self._do_plot_spectrum,
-                                                                      errors=False))
-        workspacewidget.plotSpectrumWithErrorsClicked.connect(functools.partial(self._do_plot_spectrum,
-                                                                                errors=True))
-        workspacewidget.plotColorfillClicked.connect(self._do_plot_colorfill)
+        self.workspacewidget.plotSpectrumClicked.connect(functools.partial(self._do_plot_spectrum,
+                                                                           errors=False))
+        self.workspacewidget.plotSpectrumWithErrorsClicked.connect(functools.partial(self._do_plot_spectrum,
+                                                                                     errors=True))
+        self.workspacewidget.plotColorfillClicked.connect(self._do_plot_colorfill)
 
     # ----------------- Plugin API --------------------
 
diff --git a/qt/python/mantidqt/widgets/src/_widgetscore.sip b/qt/python/mantidqt/widgets/src/_widgetscore.sip
index bc5b92838e6db8ea32ae69443114b0c06f2e3f17..d1d88d5c93b369e4b58249f7aa8e2d6e6e466d97 100644
--- a/qt/python/mantidqt/widgets/src/_widgetscore.sip
+++ b/qt/python/mantidqt/widgets/src/_widgetscore.sip
@@ -214,8 +214,7 @@ class WorkspaceTreeWidgetSimple : WorkspaceTreeWidget {
 #include "MantidQtWidgets/Common/WorkspacePresenter/WorkspaceTreeWidgetSimple.h"
 %End
 public:
-  WorkspaceTreeWidgetSimple(MantidDisplayBase *mdb /Transfer/,
-                            QWidget *parent /TransferThis/ = nullptr);
+  WorkspaceTreeWidgetSimple(QWidget *parent /TransferThis/ = nullptr);
 
 signals:
   void plotSpectrumClicked(const QStringList & workspaceName);
diff --git a/qt/widgets/common/inc/MantidQtWidgets/Common/WorkspacePresenter/WorkspaceTreeWidgetSimple.h b/qt/widgets/common/inc/MantidQtWidgets/Common/WorkspacePresenter/WorkspaceTreeWidgetSimple.h
index f76534fb0847b2925e24dc55a031794abb74abab..d7e90f9b742132facbfc68ec8b2928fc510608b0 100644
--- a/qt/widgets/common/inc/MantidQtWidgets/Common/WorkspacePresenter/WorkspaceTreeWidgetSimple.h
+++ b/qt/widgets/common/inc/MantidQtWidgets/Common/WorkspacePresenter/WorkspaceTreeWidgetSimple.h
@@ -50,9 +50,7 @@ class EXPORT_OPT_MANTIDQT_COMMON WorkspaceTreeWidgetSimple
     : public WorkspaceTreeWidget {
   Q_OBJECT
 public:
-  explicit WorkspaceTreeWidgetSimple(
-      MantidQt::MantidWidgets::MantidDisplayBase *mdb,
-      QWidget *parent = nullptr);
+  explicit WorkspaceTreeWidgetSimple(QWidget *parent = nullptr);
   ~WorkspaceTreeWidgetSimple();
 
   // Context Menu Handlers
diff --git a/qt/widgets/common/src/WorkspacePresenter/WorkspaceTreeWidgetSimple.cpp b/qt/widgets/common/src/WorkspacePresenter/WorkspaceTreeWidgetSimple.cpp
index f2cf6ba371eff3e1203c185a6784cf6da914fa0d..f739fc495c41b7efc26f63991588774a93a25dad 100644
--- a/qt/widgets/common/src/WorkspacePresenter/WorkspaceTreeWidgetSimple.cpp
+++ b/qt/widgets/common/src/WorkspacePresenter/WorkspaceTreeWidgetSimple.cpp
@@ -1,6 +1,7 @@
 #include "MantidQtWidgets/Common/WorkspacePresenter/WorkspaceTreeWidgetSimple.h"
 #include <MantidQtWidgets/Common/MantidTreeWidget.h>
 #include <MantidQtWidgets/Common/MantidTreeWidgetItem.h>
+#include "MantidQtWidgets/Common/MantidTreeModel.h"
 
 #include <MantidAPI/AlgorithmManager.h>
 #include <MantidAPI/FileProperty.h>
@@ -17,9 +18,8 @@ using namespace Mantid::Kernel;
 namespace MantidQt {
 namespace MantidWidgets {
 
-WorkspaceTreeWidgetSimple::WorkspaceTreeWidgetSimple(MantidDisplayBase *mdb,
-                                                     QWidget *parent)
-    : WorkspaceTreeWidget(mdb, parent),
+WorkspaceTreeWidgetSimple::WorkspaceTreeWidgetSimple(QWidget *parent)
+    : WorkspaceTreeWidget(new MantidTreeModel(), parent),
       m_plotSpectrum(new QAction("spectrum...", this)),
       m_plotSpectrumWithErrs(new QAction("spectrum with errors...", this)),
       m_plotColorfill(new QAction("colorfill", this)) {