Thank you PatH57!
I have focussed on the temporary Grub boot configuration with your help. The location of the nomodeset is apparently before the "quiet splash" statement. There appears to be some variation in the statement order described by different authors. I am happy with putting both the graphics "nomodeset" statement and the Broadcom chipset bug statement "b43.blacklist=yes" before that of "quiet splash". It appeared to work without fail in this order. Any confirmation?
I read carefully and located an instruction to edit /etc/default/grub with either gedit or nano
Here the instructions at, http://askubuntu.com/questions/38780/ho ... 8782#38782
, to add the nomodeset statement (and in my case the b43 chipset statement) differed from other instructions as described above but also included is a precise guide to manually edit the correct Grub file to avoid the need to manually edit the Grub boot options every time the machine is started so the following line:
GRUB_CMDLINE_LINUX_DEFAULT=<etc> + "quiet splash" + <etc>
GRUB_CMDLINE_LINUX_DEFAULT=<etc> + " nomodeset b43.blacklist=yes quiet splash " + <etc>
where for different systems there may be <etc> other arguments included; but this is not always the case.
The laptop does now boot extremely quickly and reliably. All I have to do now is to find the correct references for the firmware and the driver for my particular Broadcom wireless chipset to enable WiFi .
I am grateful for your attention to my trouble in getting these problems sorted. Your support has been much appreciated and you have kept my focus where it needed to be. I wish you all the very best in your own interests. I have learned a great deal today and my confidence in working with Linux has improved despite what appeared to be at the beginning of the day a Himalayan mole hill.