That call was the best I've made in some time. By chance I spoke with a guy, Cormac, in a local company, Crosshaven Computers here in Cork, and he strongly recommended giving Alison in East Anglian Data Recovery Services. An urgent check on the Web and I found a few reputable looking outfits but I was really disappointed with the responses from the 'experts' I spoke with. In over 30 years of working with PCs and all the variants thereof, I had never required 'data recovery'. After years of exhorting colleagues to back up regularly, I was the victim of my own stupidity.
The drive had fallen from a desk onto a hardwood floor and was not in a good way. I've just had the good news that all my video files, including documentary footage shot over 7 months, have been recovered from an external 3TB drive.