Like I said, she conflates immigrants with ethnic minorities. To vote you have to be resident. And of course many immigrants are white European.
In fact 45% of the UKIP list candidates for the London Assembly were ethnic minority and mixed race. Plus they only won 2 seats.
In local elections UKIP polls at 7% in London compared to 20% in the country. They didn't pick up a single councillor in Redbridge, Merton, Richmond, Sutton, Enfield, Haringey or Wandsworth.
UKIP attribute their relative failure in London to its 'media savvy and educated population', its 'cultured elite'.(UKIP's own words).
London has its own councils, networks, newspapers, radio stations etc, polls take the 'political temperature' on a regular basis.