Salisbury's representative in Parliament, John Glen, said the "stupid stunt" mocked the serious events that took place in the city. Ex-spy Sergei Skripal and his daughter, Yulia, were poisoned with the military grade nerve agent Novichok in March 2018.
The local police department said in a statement it was aware of the flag but said it was "not a police matter." Both Skripals survived after weeks in the hospital. British officials have blamed their poisoning on Russian military intelligence. Moscow has denied wrongdoing.