Just a further update from my original post and further to suggestions from various members:
I now have my old Mk.1 "B" RPi running merrily on DSLStats harvesting HG612 stat's. to MDWS, RPi on latest Raspbian Jessie, running headless with TightVNC / VNC Server from my Windows 8.1 desktop PC..
Had issues with getting TightVNC running after a re-boot of the RPi, eventually sorted by inserting the re-start command in /home/pi/.config/lxsessions/LXDE-pi existing autostart file, would not work for me in the /home/pi/.config folder within a new file as suggested by most web sites.
My old RPi struggled a bit at times with CPU usage, peaks just after data sampling, I have optimised the memory split to 128Mb. for GPU (default is 64Mb.) found this quite strange, would have thought that decreasing GPU allocation would have helped the CPU to recover, however, having tried step changes in both directions from the default 64Mb. can state that 128Mb. GPU allocation appears to be the best compromise.
I had purchased a RPi 3 for DSLStats/MDWS service, this obviously runs the set up with less trouble, however, as the old RPi seems to be doing the business I am currently keeping the RPi 3 in reserve for future projects, the old RPi is not really fit for present day, more demanding applications anyway, good to be able to finally but the old Pi into service.
I note there have been a lot of issues reported regarding getting DSLStats to auto-start on boot up, especially when running headless via VNC connection, this does not really bother me, I am quite content to manually start DSLStats and accept that the monitor won't run after a power outage unless re-started manually.
I find the MDWS on line facility fantastic, congratulations to the creator/custodian for the facility, and indeed to the creator/custodian of DSLStats for the provision of this excellent monitor.
Many thanks to all who offered suggestions and help, much appreciated.