Transport for London (TfL) carried out rail grinding at Finchley Central in June 2020. As this is a tight curve, train wheels are slowly wearing the rail back into a comfortable equilibrium, which is causing the noise. This is normal and is expected to reduce in time through the passage of trains. TfL is monitoring the bedding-in progress.
At Mornington Crescent, noise measurements were taken recently, and TfL is currently reviewing the results to identify the most appropriate solution. I have asked TfL to update you once this has been completed.
At Warren Street, TfL has undertaken a number of interventions, including the installation of track fasteners and flat-bottom rail conversion works, which have successfully reduced noise levels. When rail grinding is next carried out on the Victoria line, TfL will assess the levels of corrugation in this area, to determine whether it would benefit from rail grinding.
TfL continues to regularly monitor all known hotspot locations, to respond with the most appropriate and practicable mitigations.