Failed to install Grub during installation

I am running a MedionAMD A8-5500 APU with Radeon(tm) HD Graphics × 4 system with Windows 8 on the primary drive.

I had an installation of Ubuntu 12.04 on a plug in 1TB USB drive - mapped as \sdc. Grub was installed on the plug in drive so that the PC would boot directly to Windows if the drive was not plugged in and give GRUB options when the drive was plugged in.

I intially attempted an upgrade of 12.04 to 14.04. This appeared to complete successfully but on reboot GRUB would fail to run and went directly to "Grub Rescue>".

I attempted to follow the boot repair process on Ubuntu wiki- this failed to complete correctly leaving the PC in the same state.

Finally I attmempted a full install from a USB stick. All complted until it crashed out having failed to install grub.

I hope the auto generated bug splat has been automatically attached to this but found the Launchpad startup itself buggy.

Suggestions?

ubuntu@ubuntu:~$ lsb_release -rd
Description: Ubuntu 14.04 LTS
Release: 14.04

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: ubiquity 2.18.7 [modified: lib/partman/automatically_partition/question]
ProcVersionSignature: Ubuntu 3.13.0-24.46-generic 3.13.9
Uname: Linux 3.13.0-24-generic x86_64
ApportVersion: 2.14.1-0ubuntu3
Architecture: amd64
CasperVersion: 1.340
Date: Sat Jul 19 10:05:17 2014
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz.efi file=/cdrom/preseed/ubuntu.seed cdrom-detect/try-usb=true persistent noprompt floppy.allowed_drive_mask=0 ignore_uuid boot=casper quiet splash --
LiveMediaBuild: Ubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140417)
ProcEnviron:
 LANGUAGE=en_GB.UTF-8
 PATH=(custom, no user)
 LANG=en_GB.UTF-8
 SHELL=/bin/bash
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)