Some 20,000 officers from 43 police forces across England and Wales, including the Midlands, are expected to attend protests in London today.
Shadow Home Secretary Yvette Cooper says the numbers of people attending demonstrates the concern that many officers are feeling.
More top news
More than 30 officers from HMRC searched three residential and one business address during morning raids in the West Midlands yesterday.
Deputy party leader Tom Watson said that what has happened with Jeremy Corbyn is a "great tragedy".
Prince Harry has become royal patron of a Silverstone project designed to celebrate the history of British motor racing.