Courtesy of a replacement HD (exact same make and model) from Ebay for £19, I have managed to repair and recover my data-losses from last week. In the space of a couple of minutes (at least once I'd recovered a security screwdriver - the star shaped one) I'd removed and swapped the controller PCB's on the boards. I popped the old drive back in the 2nd bay and hey-presto! Colour me chuffed.
I've now managed to pull all the docs from it and set it up after a rigid format as a back-up drive (there were no surface errors, it was simply a controller board failure) - get in!
It does beg the figures discussed by recovery experts though, £70-80 to just look at the drive, then hundreds (if not thousands) to recover data. Took me 5mins and £19 once I'd tracked down an identical drive :)