Adding custom toolbar icons in PyQGIS

I am following a tutorial at https://courses.spatialthoughts.com/pyqgis-in-a-day.html
that gives some instructions on how to set up a new toolbar item with a custom icon in a QGIS map using PyQGIS in the integrated python console

import os
from datetime import datetime

icon = 'question.svg'
data_dir = os.path.join(os.path.expanduser('~'), 'Downloads/pyqgis_in_a_day/')
icon_path = os.path.join(data_dir, icon)
print(icon_path)

def show_time():
    now = datetime.now()
    current_time = now.strftime("%H:%M:%S")
    iface.messageBar().pushMessage('Time is {}'.format(current_time))
    
action = QAction('Show Time')
action.triggered.connect(show_time)
action.setIcon(QIcon(icon_path))
iface.addToolBarIcon(action)

The code runs without error but no icon gets placed in the toolbar area of QGIS
I have checked the path to the icon and tested that also by supplying the full path, copy and paste, to avoid typos but no success. I am using QGIS version 3.14 and checked over the documentation and the methods seem to be correctly

Can anyone see what I might be doing wrong?