ChrisD - Thanks for the last advice, but want to keep life simple.
Looked again on NAS server and found a hidden setting to turn on DNLA, FTP is also still turned on, but HDR still cannot find the NAS. I can't help thinking I must be missing something obvious! Should I not have both turned on?
On the positive side - attached an external HDD to the HDR (preformatted in Ext3 using Acronis software on my PC), copied both a standard def and a high def film to the external HDD and used Filezilla (which could see the external drive as well as the HDR) to copy both to the NAS. The standard definition film can now be played back on any networked PC or laptop using VLC, but not the high definition film. Therefore have a means of backing up/storing all recordings on my NAS and a means of playing back all standard def recordings anywhere in the home. Very significant progress, but miffed that I can't see the NAS from the HDR which would make life much easier. Like everyone else I will have to wait for a straightforward way of watching high def recordings on networked Pcs/laptops.