They are happy to receive unsolicited manuscripts from authors but you need to follow the guidelines on their web site and check that your work is suitable for their list.
All submissions should be marked for the attention of the Publisher’s Reader and sent by post to:
They currently welcome non-fiction and crime fiction book ideas and synopses. For further information visit the Constable & Robinson website.
Constable & Robinson3 The Lanchesters
162 Fulham Palace Road