Initially, the novels were not linked to the previous Virgin New Adventures series of books (which had included one Eighth Doctor novel). Even so, as the series progressed and more writers from the Virgin line came to write for the EDA series, the barriers began to come down and many books contain characters and references to events in the Virgin series. After the launch of the EDA line, BBC Books launched two spin-off series of books: the BBC Past Doctor Adventures line and the Short Trips short story collections.