Thanks for the reply. I tried the following based on your suggestions:
1) Uninstalled the current driver, an Intel HD Graphics Family Driver (25/03/2011 Version 8.15.10.2342) and rebooted, whereupon the system came back up with a VgaSave Device(?)/Driver that provided basic functionality- NO projector, RGB, HDMI output or even the options in BOTH SAFE AND NORMAL MODES (W7 32 Bit). In Device Manager this shows up under 'Other Devices' (Video Controller (VGA Compatible). Expected result.
2) Searched for a new driver with Update Driver- the system found and installed an Intel HD Graphics Family Driver (12/12/2012 Version 9.17.10.2932) so this is an improvement. RGB output no problem, it recognizes this as an LG TV (correct). Plugging HDMI cable into the PC, the driver seems to recognize a 3rd display (LG TV) but it seems to be trying to output to the VGA Port- it's as if it senses an HDMI Port (and an LG TV from data coming in) but can't move data out along the HDMI connection.
That's the state of play at present. I'd have used the driver you kindly referred to, only it's 64 Bit and my system is W7 32 Bit- would you have a link to the 32 Bit version? Then I'll try that to see results and if it doesn't work I'll revert back to identify the permutations/combinations of VGA AND/OR HDMI lead connections to the TV and the results for VGA only (seems to work fine), HDMI only and both plugged in.
Any other suggestions and believe me, I'm all ears.
Thanks again for your help- it is very much appreciated.