Clicking noise from rear wheel (Non Clio)

[172_Cup_Lew]

My mum has a 1.6 convertible Mini, it recently had the rear discs and pads changed and since then its developed a clicking noise from the rear left wheel which increases as the speed of the car does, the wheel bearings been changed so it isn't that, any ideas?

Thanks

 

[Henry]

something in the tyre tread?

 

[172_Cup_Lew]

something in the tyre tread?

unfortunately not

theres nothing loose either i just had a look, so its not the brake line or anything like that