Brake hum/honk while light braking?

[RipGroove]

I've ruled out contamination completely now this morning, as it stands the rotor, pads, return spring and retaining pin have all been swapped front to rear and the noise has stayed at the front. Albeit it's quieter than yesterday since replacing the cracked top cap. I'll go get a better fitting top cap from my LBS this morning and see if that makes any difference at all.

 

[RipGroove]

New Hope top cap and bolt fitted and after 10 mins testing on a quick ride the noise is now only present under very light braking which is much more managing than yesterday when it was honking like mad under light and medium braking, now medium braking is silent with the only change being a new top cap. I'll give it a more substantial ride later and report back again.