Gerard Batten claims it it the latest of a series of attempts to intimidate UKIP activists and campaigners across the UK.
Gerard Batten added:
"We have seen UKIP premises vandalised, billboards destroyed and elected representatives, campaigners and activists targeted with physical and verbal abuse. Many if not all of these attacks appear to have been driven by the hard left and their allies operating under the guise of 'anti-racism'."
More top news
Clashes between rival supporters marred West Ham's EFL Cup fourth round win over Chelsea at the former Olympic Stadium
Damon Smith, 19, has been charged with making or possessing an explosive substance with intent to endanger life.
Photographer Jeffrey Milstein flew over the capital and took some pretty eye-catching images