I have seperated this story from the last, even though its derived from a discussion with Pam, because it would be easier for someone to find if they also needed this information.
In discussion over the Easter with Pam re her issue with not being able to clip the tiller extension to the tiller.
This I guided her through with a few pictures and detail of what drill sizes to use, and duly sent her a pin in the post Free of charge. The pictures are shown below and clearly show the process from tools needed through to clipping the extension to the tiller. If anyone has any questions on this process or products then please get in touch.