After many I attempts I wasn't able to archieve the same result as in @Daniel Muirhead's example. For some reason Sketchfab doesn't process the texture properly. It seems like it's only showing me the shaded model (coloured faces) rather then the proper texture.
I therefore tried another format,(.dae) which required a bit of messing around with the settings in sketchfab, but at least looks decent (ish).