Thanks for the links, yeah I was aware of the non standard Vegas adapter mount sony supplied but was hopping there would be other alternatives which you have pointed to possible ones. Regarding that Sony vesa adapter just does seem that secure as its only using 2 mounting screws to attach itself to the back of the TV.
My only issue now if I'm going to use the mounting bracket set you linked from Amazon is what to do about the PSU brick as the cable that runs from the back of the TV to the brick won't be long enough now. I guess I could try and find a male to female extension cable but I'm not sure what tip size is use for the power cable!?
Yeah i don't like how that adapter box thingy only utilizes two mounting screws, but the TV is pretty light and Sony must think it's strong enough for wall mounting, but i'd be concerned with an articulated mount.
As for the power brick, i think that rectangular opening in the Sony adapter box might be a holder for the brick (can't tell by the picture if it's large enough or not).
My 55" W800B is mounted on a Peerless PLA50 articulated arm mount and i zip-tied the power brick to the arm directly behind the TV. I don't think you'll ever find a male/female extension cable for the power end of that brick.
However, i think i'd be more inclined to use the male/female extension screw kit instead as it looks like those two super long screws are intended to use at the bottom to reach through the thick area at the bottom of the TV and thread in to the same holes that the table stand's screws would normally thread into, so you end up with four mounting points on the TV. I'm also presuming that the distance between the upper left and right holes is the same as the distance between the two lower stand holes. I'm also presuming you're in the UK, or maybe Europe since that TV doesn't come up on US sites.
Here's another source for the screw kit:
http://www.av4home.co.uk/sony-w6-7-8-bolt-kit.html#prodTop