This is a Insert Setright ticket where the conductor carried a pack of blanks similar to the Bell Punch ticket but they had an area for overprinting by the conductor. There were dials on the side of machine for the setting of the fare and fare stage the date would also be set the once at the start of the shift. When all dials were set the ticket was inserted hence its name into the machine and was overprinted over the red wavy lines in the case of the above. This system had the big advantage over the Punched system in that the conductor had to carry far less tickets single, return and other specials instead of a ticket for each value. Another big advantage of the Insert Setright ticket system was that the machine clocked up the total number of tickets issued and the total value saving many hours of ticket counting. The value of the ticket in the case above is printed in letters but I do have other tickets of the same system where the value is printed in numbers not sure if there is anything in that or was there just a choice if you know please leave a comment. The above ticket by the way was printed by Bell Punch London.