Hi - a week ago the front nearside brake on my 2014 Qashqai seized, leading to clouds of smoke and only just got to park it.  2 hours later the RAC man found that he could drive it but there was a knocking noise.  'Take it to the garage'.  This I did - to a Nissan garage - without trouble but the noise is still there.  The garage can't find the cause either!  The noise is a bit like if there was a stone in the tyre.  Any comment?

Was there anything that caused the initial lock-up? driving on a dirt track? anywhere a stop could have been introduced into the braking assembly?