Len and the River Mob was a ten-part Look and Read serial produced by the BBC in 1968, it was written by Roy Brown.

Later, Len asks Bill if he knows who stole the toys and he replies that there is a gang called "The River Mob" who are operating around the docks and that they are the prime suspects.

Bill hands Len a police note that says that a crate, marked "996/HO", containing an engine, was stolen the week before and tells him to keep an eye out for it.

Len checks its marking, "OH/966", against that of the number Bill gave him, dismissing it as a different box before he and Micky are told to put it in the shed.

Len and Pat head home but on their way pass Mr Moon's shed, which is open, and hide inside to see what is going on.

The dog comes and picks it up but when Bill reads it he cannot see Len and says that he shouldn't have left the note lying around.

When Bill sees the message he rushes to the shed and frees Len, who tells them that they must find crate before it reaches the Samba.