"appalled that [city mayor] Sadiq Khan has approved such....surveillance technology for London"
I'm not surprised at all. Remember that Labour under Blair and Brown pushed through or carried on with all the GCHQ nastiness that Edward Snowden uncovered. And there was ID card-gate under Labour. Then Labour topped that off by taking CCTV and license plate readers national.
Not that the Conservatives have proven themselves better when it comes to mass surveillance, but they absolutely haven't proven themselves worse either.