20 thousand police officers - including more than 500 from Avon and Somerset have started a march through London in protest against planned government cuts.

The officers, who are all off-duty because they're banned from striking under law, are wearing black caps representing each person expected to be lost under the plans.

The local Police Federation estimates 700 could go here - which would impact on public safety.

But Policing Minister Nick Herbert says it's just about changes to pay and conditions.