Scottish First Minister Nicola Sturgeon has said she believes it is "a matter of when, not if" Boris Johnson is forced out of office over the Downing Street party scandal.

Launching the SNP's local election manifesto on Friday, the party leader criticised the prime minister as a "clown" whose conduct and policies were "not funny". Report by Buseld. Like us on Facebook at http://www.facebook.com/itn and follow us on Twitter at http://twitter.com/itn