Right I have managed to find the area where the ticking is coming from (without a second person around

1) Aux belt is highly unlikely to be the source.
2) I don't think the area it is coming from is the tappets (but I could be wrong)
The area from the bonnet where the sound is most prominent is coming from here: (excuse the poor camera quality!)
Moving my head over the top back of the engine it is definitely quieter, even took off the main engine cover, no difference in volume.
So seems to be something down there to the right of the engine making the noise.
Would the tappets be heard more from down there or could it be something else?
Thanks
Ben