The battery is eight (8) years old, but it has never given any problems. It was fully charged when the camera switched off.
The camera has never been dropped or subjected to any shocks.
No excess temperatures (+/-) applied to camera.
No exposure to undue humidity or water.
No exposure to grit, etc.
As a last resort I bought a new CF card this morning and tried again, but nothing happens, i.e. the camera is not powering up. I have tested the rechargeable battery and it shows full voltage, however, maybe the age of the battery is such that I ma not getting the Amperage.
I think the next logical step is - as you have suggested - to renew the battery. If that works fine otherwise I shall have to send it to Canon for their opinion.
Thank you for your assistance which is appreciated. If you are interested in further findings do let me know how I can send you an email.
Regrettably, the camera remains dead after installing a new and fully charged battery. I shall have to send it to Canon for opinion and repairs.