Decided to put it back into Evans - the bike is only a week old after all. Narrowed it down to the area I described. Thankfully after a 10 mile ride into London and 'tick tick tick' all the way in it repeated it in front of a mechanic. He found if he applied pressure on the tyre in the area I described it made that popping tick sound

Basically they replaced the tube and re sat new rim tape plus pumped the wheel up to 110 psi. Which seems to have solved the problem - didnt hear a thing last night over 10 miles.

Sounds like the rim tape inconjuction with the tube only 75% inflated was not fitted properly in the factory and it was catching every time the wheel rotated and applied pressure in a certain spot.

Sounds feasible anyone?